Top 5 questions related to Ratio for class 8.

1.If the ratio of chocolates to ice-cream cones in a box is 5:8 and the number of chocolates is 30, find the number of ice-cream cones.

Solution:

Let the number of chocolates be 5x and the number of ice-cream cones be 8x.

5x = 30 

→ x = 6.

Therefore, number of ice-cream cones in the box = 8*6 = 48.

2.Two numbers are in the ratio 3 : 4. If the sum of numbers is 63, find the numbers.

Solution:

Sum of the terms of the ratio = 3 + 4 = 7

Sum of numbers = 63

Therefore, first number = 3/7 × 63 = 27

Second number = 4/7 × 63 = 36

Therefore, the two numbers are 27 and 36.




3. If x : y = 1 : 2, find the value of (2x + 3y) : (x + 4y)

Solution:

x : y = 1 : 2 means x/y = 1/2

Now, (2x + 3y) : (x + 4y) = (2x + 3y)/(x + 4y) [Divide numerator and denominator by y.]

= [(2x + 3y)/y]/[(x + 4y)/2] = [2(x/y) + 3]/[(x/y) + 4], put x/y = 1/2

We get = [2 (1/2) + 3)/(1/2 + 4) = (1 + 3)/[(1 + 8)/2] = 4/(9/2) = 4/1 × 2/9 = 8/9

Therefore the value of (2x + 3y) : (x + 4y) = 8 :9.

4. A bag contains $510 in the form of 50 p, 25 p and 20 p coins in the ratio 2 : 3 : 4. Find the number of coins of each type. 


Solution: 

Let the number of 50 p, 25 p and 20 p coins be 2x, 3x and 4x. 

Then 2x × 50/100 + 3x × 25/100 + 4x × 20/100 = 510

x/1 + 3x/4 + 4x/5 = 510

(20x + 15x + 16x)/20 = 510 

⇒ 51x/20 = 510

x = (510 × 20)/51 

x = 200

2x = 2 × 200 = 400 

3x = 3 × 200 = 600 

4x = 4 × 200 = 800. 

Therefore, number of 50 p coins, 25 p coins and 20 p coins are 400, 600, 800 respectively. 

5.Set up all possible proportions from the numbers 8, 12, 20, 30.

Solution:

We note that 8 × 30 = 240 and 12 × 20 = 240

Thus, 8 × 30 = 12 × 20       ………..(I)

Hence, 8 : 12 = 20 : 30       ……….. (i)

We also note that, 8 × 30 = 20 × 12

Hence, 8 : 20 = 12 : 30       ……….. (ii)

(I) can also be written as 12 × 20 = 8 × 30

Hence, 12 : 8 = 30 : 20       ……….. (iii)

Last (I) can also be written as

12 : 30 = 8 : 20       ……….. (iv)

Thus, the required proportions are 8 : 12 = 20 : 30

8 : 20 = 12 : 30     12 : 8 = 30 : 20     12 : 30 = 8 : 20

Comments

Popular posts from this blog

Name the largest Dam of India..

भारत के विभिन्न में परमाणु केंद्रों को याद रखने का जीके ट्रिक। GK trick to remember some atomic Power station of India

भारतीय नगरों एवं महानगरों के उपनाम