Mallapragada's Mathematics - (7th standard-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%