Question

A boy measured the length and breadth of rectangular lawn as 96.6m and 40.3m respectively instead of 60m and 40m.what is the percentage error in his calculation of the perimeter of the lawn?

Answer 1

perimeter 1 = 2(96.6) + 2(40.3) = ?
Perimeter 2 = ?

(1-2)/2 = ?
Change to percentage

Answer 2

It's the actual error divided by the true amount:
96.6 vs 60 for the length? Gotta be a typo of major proportions. I shall assume you meant 60.6

((60.6+40.3) - (60+40))/(60+40) = (100.9 - 100)/100 = 0.9/100 or 0.9%
yeah, I know there's factor of 2 missing, but it appears everywhere, so it cancels out.