If x varies indirectly to y² and if x = 78, y = 11, then find the value of x when y = 2.2

Correct option is A

Given:

xx varies inversely to y²

When x = 78, y = 11

We need to find the value of x when y = 2.2

Concept Used:

When x varies inversely to y², 

​$$x \propto \frac{1}{y^2}$$​​

​$$x \times y^2 = k$$​​

where k is a constant.

Solution:

First, finding the constant k using the given values x = 78 and y = 11:

$$78 \times 11^2 = k \\ \ \\78 \times 121 = k \\ \ \\k = 9438$$​​

Now, 

$$x \times 2.2^2 = 9438 \\ \ \\x \times 4.84 = 9438 \\ \ \\x = \frac{9438}{4.84} \\ \ \\x = 1950$$​​

Thus, the value of x when y = 2.2 is 1950