30. Mallapragada's Mathematics -7th Standared (7)

1.Rama has a road map with a scale of 1cm representing 18km.  She drives on a road for 180km.  What would be her distance covered in the map.

2. In a school x. 72 students  appeared  for 10^th class exam out of which 36 students.  In another school y, 30 students appeared and 24 students passed.  If the D.E.O. wants to give  an award on the basis of pass percentage, to which school will he give the award.

3. Last year the cost of 1000 articles was Rs. 5000.  This year it goes down to 4000.  What is the percentage of decrease in price?

4. Out of 12,000 voters in a constituency, 60% voted.  Find the number of people voted in the constituency.

5. A local cricket team played 20 matches in one season.  If it won 25% of them and lost rest, how many matches did it loose.

6. In every gram of gold, a gold smith mixes 0.25gm of silver and 0.05 of copper .  What is the percentage of gold, silver and copper in every gram of gold.

7.a shopkeeper bought a suitcase for Rs. 480 and sold it for Rs. 540.  Find his gain percent?

8. Rama bought a T.V. for Rs. 15,000 and sold it for Rs. 20,000.  Find the gain percent ?

9. Ramu sold a plot of land for Rs. 2,40,000 gaining 20% For how much did he purchase of the plot.

10. On selling a mobile for Rs. 1000, a shopkeeper loses 10% For what amount should be sell it to gain 5%?

11. a former sold 4 bullocks for Rs. 24,000 each.  On one bullock he gained 25% on the other he lost 30% Find his total profit or loss percent. 

12.Rama bought a watch for Rs. 480.  He sold it to Krishna at a gain of 6 ¼% Krishna sold it to divya at a gain of 10% How much did Divya pay for it?

13.The marked price of a book is Rs. 225.  The publisher allows a discount of 10% on it.  Find the selling price of it.

14. A carpenter allows 15% discount on his goods.  Find the marked price of a chair which is sold by him for Rs. 850

15. a dealer allows a discount of 10% and still gains by 10%. What should be the marked price if the cost price is Rs. 1000

1.Rama has a road map with a scale of 1cm representing 18km.  She drives on a road for 180km.  What would be her distance covered in the map.

Scale of the map is 1 cm.  = 18km., Distance covered 180km.

Let it be x cm map , than  1: 18 :: x : 180

18 x = 180       There fore x = 180/18 = 10 cm.

2. In a school x. 72 students  appeared  for 10^th class exam out of which 36 students.  In another school y, 30 students appeared and 24 students passed.  If the D.E.O. wants to give  an award on the basis of pass percentage, to which school will he give the award.

No.of  students appeared 10^th class = 72

No. of students passed = 36, percentage = 36/72 x 100 = 50%

No. of students appeared = 30, passed students = 24

Pass percentage = 24/30 x 100 = 80% , 80%>50%

3. Last year the cost of 1000 articles was Rs. 5000.  This year it goes down to 4000.  What is the percentage of decrease in price?

Cost of 1000 Articles = 5000, cost of one article = 5000/1000=5

Cost of 1000 Articles = 4000, cost of one article =4000/1000=4

Decrease in price = Rs. 5 – Rs. 4 = Rs. 1

Decrease of % = 1/5 x 100 = 20%

4. Out of 12,000 voters in a constituency, 60% voted.  Find the number of people voted in the constituency.

Percentage of people = 60% of 12,000

No. of people voted = 60/100 x 12000 = 7,200

5. A local cricket team played 20 matches in one season.  If it won 25% of  them and lost rest, how many matches did it loose.

Total No. of matches played = 20

Matches won = 25%, Matches lost = 100 – 25 = 75%

There 75% of 20 = 75/100 x 20 = 15

6. In every gram of gold, a gold smith mixes 0.25gm of silver and 0.05 of copper .  What is the percentage of gold, silver and copper in every gram of gold.

The Quantity of silver = 0.25 gm,

The quantity of copper =0.05 gm.

The quantity of gold = 1gm – (0.25 + 0.05)= 1.00 - 0.30= 0.70gm

Percentage of gold = 7/1 x 100 = 70%

Percentage of silver = .25/1x100 = 25%

Percentage of copper= .05 /1 x 100 = 5%

7.A shopkeeper bought a suitcase for Rs. 480 and sold it for Rs. 540.  Find his gain percent?

Gain = Sp –CP = 540-480= 60,

 Gain % = 60/480 x 100 = 10/8=12.5%

8. Rama bought a T.V. for Rs. 15,000 and sold it for Rs. 20,000.  Find the gain percent ?

Gain= S.P. –CP = 20,000-15,000 = 5,000

Gain % = 5000/15000 x 100 = 100/3= 33.3%

9. Ramu sold a plot of land for Rs. 2,40,000 gaining 20% For how much did he purchase of the plot.

Let C.P.= x, Gain % = 20% of C.P.   S.P. of land =120% of c.P

120% of  x /100 = 24000 = There fore x =100 x 24000/120 =

Ans. Rs. 2,00,000

   

10. On selling a mobile for Rs. 750, a shopkeeper loses 10% For what amount should be sell it to gain 5%?

Let tha c.p of mobile = x  S.P. = 750, loss %= 10  loss= 10x/100

S.P.= C.P.- Loss = x – 10 x/100 =90x/100

There fore 90x /100 = 750, x = 750 x 100/90 = 2500/3

Now tha gain 5% of S.P.= c.P. + 5% of C.P

2500/3 + 5/100x2500/3 =2625/3 = Rs. 875

11. a former sold 2 bullocks for Rs. 24,000 each.  On one bullock he gained 25% on the other he lost 30% Find his total profit or loss percent. 

S.P.= C.P. + Gain = x + 25x/100 = 125x/100 = 24,000

X = 24,000 x 100/125= 19,200

S.P.= C.P.- Loss = y – 20x/100 = 80y/100 = 24,000

Y= 24000  x 100/80 = 30,000

Total C.P. of 2 bullocks = 19000+ 300000= 49,200

Toal S.P. of to bullocks = 24000x 2 = 48000

Loss = c.P.-s.P = 1200

Loss % = 1200/49200 x 100 =2.4%

   

12.Rama bought a watch for Rs. 480.  He sold it to Krishna at a gain of 6 ¼% Krishna sold it to divya at a gain of 10% How much did Divya pay for it?

Cast price of Watch = 480

Gain% = 6 ¼% =25/4%   Gain % = 480 x25/4 x 1/100 = 30

C.P= 480 + 30 =510

Gain = 510 x 10 /100 = 51

S.P. = 510 + 51 = Rs. 561

13.The marked price of a book is Rs. 225.  The publisher allows a discount of 10% on it.  Find the selling price of it.                                                                  

M.P. of the book = Rs. 225-00

Discount = 10%  discount = 225 x 10/100 = Rs. 22.5

S.P. = M.P.- discount = 225.00 - 22.50 = Rs. 202.50

14. A carpenter allows 15% discount on his goods.  Find the marked price of a chair which is sold by him for Rs. 850

Let the M.P. of chair. = x

Discount = 15% = 15x/100

S.P. = M.P. – Discount = x – 15x/100 = 85x /100

S.P. = Rs. 850-00    There ore = 85x/100 x 850-00 =

X = 850 x 100/85 = 1000

M.P. of the chair = Rs. 1000

15. A dealer allows a discount of 10% and still gains by 10%. What should be the marked price if the cost price is Rs. 1000

Given that C.P= Rs. 1000

There is a gain of 10% on C.P.

Gain = 10% of Rs. 1000 = 10 x 1000/ 100 = 100

S.P. = C.P. + Gain = 1000 + 100 = 1100………………(1)

Let M.P. = x

Discount on it = 10% on M.P. = 10 x/100

S.P.=M.P.-Discount = x - 10x/100 =90x/100

From (1) & (2) = 90x/100 =1100    x= 1100 x 100/90 = 11000/9

30. Mallapragada's Mathematics -7th Standared (7)

1Rama has Rs. 5 Money win Krishna is 3 times the money with Rama.  How much money does Krishna have?

2. Divide 108 chocolates between Rama and Krishna in the Ratio 5:7

3. a sum of Rs. 1,00,000 is devided in the ration 3:5 What is the smaller share?

4. To make green paint. A painter mixes Yellow paint, red pain in the ration 3:2 If he used 12 liter of yellow paint, how much red paint did he use?

5. a rectangle measures 50 cm. at it length 10 cm at its width. Find the ration of length to width.

6. The speed of a farden small is 100m per hour and that of the Rama is 120 kmph. Find the ratio of the speeds.

7. Madhu buys 10kg of potatoes at the market.  If the cost of 2kg is 40 .  how much will Madhu pay?

8. Physics tells us that weight \of on objet on the moon is proportional to its weight on Earth. Suppose a 90 Kg man weight 15 kg. on the moon.  What will a 60 kg. woman weigh on the moon?

9. Sri Rama has a basket full of babanas, Oranges and mangoes.  If 5o% are bananas, 15% are oranges , then what percent are mangoes?

10. 20% + 30% +………… = 100%

11. On rainy day, out of 100 students in a school 25 were absent,.  Find the percentage of students absent from the school? What percentage of students are present?

12. The ratio of two angles is 3 : 1 Find the

(i) larger angle if the smaller is 180⁰ ,

(ii) smaller angle if the larger is 72⁰

13. 40% of a number is 1000 then find the number.

14.Population of our country as per 2012 census is about 12 x 10⁸ (120,00,00,000)If the population of our country increases by 4% every year what will be the population by 2013?

15. At what rate a sum doubles itself in 8 year 4 months?










Answers

1Rama has Rs. 5 Money win Krishna is 3 times the money with Rama.  How much money does Krishna have?

Money with Rama  = Rs. 5/- ,

Money with Krishna = 3 times Rama = 3 x 5 = 15 Rs

Rama : Krishna = 15:5  15/5 = 3/1 =3:1

Krishna : Rama = 5/15 = 1/3 = 1:3  

2. Divide 108 chocolates between Rama and Krishna in the Ratio 5:7

Ratio 5:7, Total Ratio = 5 + 7 = 12

Rama’s share = 5/12 x 108 = 45

Krishna’s Share = 7/12 x 108 = 63

3. a sum of Rs. 80,000 is deivided in the ration 3:5 What is the smaller share?

Ratio: 3:5 , Total Ratio 3+5=8

Smaller share = 3/8 x 80,000= Rs. 30,000

4. To make green paint. A painter mixes yellow paint, red pain in the ration 3:2 If he used 12 liter of yellow paint, how much red paint did he use?

yellow paint, red pain in the ration 3:2

yellow paint = 3 parts. Is 12

Quantity of Red paint = 2 parts.  2/3 x 12 = 8 litres

5. a rectangle measures 50 cm. at it length 10 cm at its width. Find the ration of length to width.

Ratio of length and width ; 50 cm : 10 cm :: 5:1

6. The speed of a garden small is 100m per hour and that of the Rama is 120 kmph. Find the ratio of the speeds.

Speed of the Garden  = 100 m/hour. 100/1000 =1/10km

Speed of the Ram = 120 kmph.

Ratio of their speeds = 1/20 :120  == 20/20 : 20 x 120 = 1:2400

7. Madhu buys 10kg of potatoes at the market.  If the cost of 2kg is 40 .  how much will Madhu pay?

Cost of 2 kg. pototos = 40 one kg pototo = 20

Cost of 5 kgs. 5x 20 = 100

8. Physics tells us that weight \of on objet on the moon is proportional to its weight on Earth. Suppose a 90 Kg man weight 15 kg. on the moon.  What will a 60 kg. woman weigh on the moon?

Man’s weight onearth  == 90 kg.

Man’s witght on moon == 50 kg.

Woman’s weight on earth = 60 kg.

Let women’s weight on moon = x

Then 90 : 15:: 60 : x      Therefore x = (15 x 60)/90 = 10 kg.

9. Sri Rama has a basket full of bananas, Oranges and mangoes.  If 5o% are bananas, 15% are oranges , then what percent are mangoes?

Percentage of Mangos = 100% - ( 50% + 15% )=35%

10. 20% + 30% +……x…… = 100%

      X = 100% - (20% + 30%) = 50%

11. On rainy day, out of 100 students in a school 25 were absent,.  Find the percentage of students absent from the school? What percentage of students are present?

 Total students = 100 , no. of students absent = 25

Present students = 100 – 25 = 75

Percentage of students : 25/100  x 100 = 25 %

Presentage of percentage students: 75/100 x 100 =75%

12. The ratio of two angles is 3 : 1 Find the

(i) larger angle if the smaller is 180⁰ ,

(ii) smaller angle if the larger is 72⁰

Then 3:1 :: x : 180    x = 3 x 180 = 540

Then 3:1 ::  72 : x      3 x  = 72    x = 72/3 = 24

13. 40% of a number is 1000 then find the number.

         Let the number : x 40% of x = 1000

         X = 1000 x 100/40 = 2500

14.Population of our country as per 2012 census is about 12 x 10⁸ (120,00,00,000)If the population of our country increases by 4% every year what will be the population by 2013?

Population in 2011 = 12 x 10⁸

 It is increases by 4% Population in 2012 = (100 +4)% of 2011

104% of 12 x 10⁸    ==( 1248 x  10⁸  )100 = 12.48 x 10⁸

  

15. At what rate a sum doubles itself in 8 year 4 months?

Given that A = double the sum

Let the principle be p   There for A = 2p

T = 8 y 4 months = 8 1/3 = 25/3 

I = A- P = 2p –p = p       I = PTR/100 == p =(p x 25/x R)/100

R= 100 x 3/25 = 12%