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If x and y are directly proportional and when x = 13, y = 39, which of the following is not a possible pair of corresponding values of x and y
(a) 1 and 3
(b) 17 and 51
(c) 30 and 10
(d) 6 and 18

Solution:

If x and y are directly proportional then we can write:

x ∝ y which implies

x = ky

x/y = k

13/39 = k

k = 1/3

Of the pairs given in the options, the pair which is not a possible pair of corresponding values of x and y is 30 and 10

So if x = 30 and y = 10 then

x/y = 30/10 = 3 = k

The value of k calculated earlier was 1/3.

✦ Try This: If x and y are directly proportional and when x = 14, y = 56, which of the following is not a possible pair of corresponding values of x and y? (a) 1 and 4, (b) 4 and 16, (c) 40 and 10, (d) 9 and 36

If x and y are directly proportional then we can write:

x ∝ y which implies

x = ky

x/y = k

14/56 = k

k = 1/4

Of the pairs given in the options, the pair which is not a possible pair of corresponding values of x and y is 40 and 10

So if x = 40 and y = 10 then

x/y = 40/10 = 4 = k

The answer is (c)

If x and y are directly proportional and when x = 13, y = 39, which of the following is not a possible pair of corresponding values of x and y (a) 1 and 3, (b) 17 and 51, (c) 30 and 10, (d) 6 and 18

☛ Also Check: NCERT Solutions for Class 8 Maths Chapter 13

NCERT Exemplar Class 8 Maths Chapter 10 Sample Problem 1