Question

In a class, the average height of 35 girls was measured 160 cm. Later on, it was discovered that the height of one of the girl was misread as 144 cm, while her actual height was 104 cm. What was the actual average height of girls in the class? (rounded off to two digits after decimal).

• A. 159.86 cm
• B. 158.54 cm
• C. 159.56 cm
• D. 158.47 cm
• E. None of these

Answer 1

The correct option is E None of these

Here, value of new quantity added-value of removed item d= $\pm$ N. x.
$\Rightarrow$ 104 - 144 = - 35 $\times$ x $\Rightarrow$ x= $\frac{40}{35}$
$\therefore$ New average $=160-\frac{40}{35}$
= 160 $\frac{8}{7}$ = 160 - 1.14
= 158.86 cm