Q.

The area between x=y2 and x=4 is divided into two equal parts by the line x=a, the value of a is:

1 4  
2 163  
3 323  
4 None of these  

Ans.

(2)

Ans.         163

Explanation :

Given, x=y2 is a parabola symmetric to the positive X-axis with vertex (0, 0).

We have given that,

                      ∫0ax dx=∫a4x dx

⇒                    [x3/232]0a=[x3/232]a4

⇒                     23a3/2=23(43/2-a3/2)

⇒   23a3/2+23a3/2=23×8

⇒                    43a3/2=163

⇒                       aa=163×34

⇒                        a3/2=4

⇒                 a=42/3=(22)2/3

⇒                 a=24/3=163