Question 53

The average of X, Y and Z is 2X. If the average of Y and Z is 20, then what is the value of X?

Solution

The average of X, Y and Z is 2X.

$$\frac{X+Y+Z}{3}\ =2X$$ Eq.(i)

If the average of Y and Z is 20.

$$\frac{Y+Z}{2}\ = 20$$

Y+Z = 40 Eq.(ii)

Put Eq.(ii) in Eq.(i).

$$\frac{X+40}{3}\ =2X$$

X+40 = 6X

6X-X = 40

5X = 40

X = 8

Value of X = 8

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