The mean of 20 observations is 50. If the observation 50 is replaced by 140, what will be the resulting mean?

Sum of 20 Observations$=20\times 50$

$=1000$

An Observation  50 is replaced by 140

New sum of 20 Observations $=1000-50+140$

$=1090$

$=\frac{1090}{20}$

$=\frac{109}{2}$

$=54.5$