#### If the mean of x1, x, is 7.5, and the mean of x1, X2, x3 is………….

**Solution:**

Mean = sum of variables/number of variables.

First equation

X1 + X2 = 7.5

2

X1 + X2 = 15 —— (1)

Second equation

X1 + X2 + X3 = 8

3

X1 + X2 + X3 = 24 ——– (2)

Subtract equation 1 from equation 2

(X1 + X2 + X3) – (X1 + X2) = 24 – 15

X3 = 9

(a) 9 is correct

**If each observation of the data is increased by 5, then their mean…………**

**Solution:**

(d) is increased by 5 is correct

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