Question:
The mean of the marks scored by 50 students was found to be 39. Latter on it was discovered that a core of 43 was misread as 23. The correct mean is
(a) 38.6
(b) 39.4
(c) 39.8
(d) 39.2
Solution:
(b) 39.4
Mean of the marks scored by 50 students = 39
Sum of the marks scored by 50 students $=(39 \times 50)=1950$
Correct sum $=(1950+43-23)=1970$
$\therefore$ Mean $=\frac{1970}{50}=39.4$