Question

Mean of 100 items is 49. It was discovered that three items which should have been 60, 70, 80 were wrongly read as 40, 20, 50 respectively. The correct mean is

• A. 48
• B. 82 $\frac{1}{2}$
• C. 50
• D. 80

Answer 1

The correct option is C 50

Sum of 100 items = 49 $\times$ 100 = 4900
Sum of items added = 60 +70 +80 = 210
Sum of items replaced =40 +20 +50 = 110
New sum = 4900 -110 +210 = 5000
$\therefore Newmean=\frac{5000}{100}=50$