Instructions

In each of the questions, a question is followed by two statements I and II. Give your answer

Question 155

If the A.M. of 4, 20, 40, x is m, then what is the value of m?
I. $$\frac{m}{x} - 5$$ = 8
II. x is less than m

Solution

Arithmetic mean of 4,20,40 and x is $$\left(4+20+40+x\right)\div4.$$

So,$$m=\left(64+x\right)\div4=\left(16+\ \frac{\ x}{4}\right).$$

I.

$$\ \frac{\ m}{x}=8+5=13.$$

or,$$\ \ m=13x.$$

So,$$\ 13x=16+\ \frac{\ x}{4}.$$

or,$$\ 51x=64.$$

or,$$\ x=\ \frac{\ 64}{51}.$$

So,$$\ m=13x=13\times\ \frac{\ 64}{51}.$$

II. x is less than m, does not signifies any value of m.

So,A is correct choice.

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If the A.M. of 4, 20, 40, x is m, then what is the value of m?I. $$\frac{m}{x} - 5$$ = 8II. x is less than m