IT Placement Practice Test 7

Given, total number of potatos = 20.
First potato 24 metres from the starting point. There are 4 meters in the intervals. A contestant is required to bring the potatoes back to the starting place one at a time. So for the first potato he has to travel 48 meters,
for second 56 meters ...
48,56,64...........20 terms.
a = 48, d= 8, n = 20.
Sum of n terms in A.P =
⇒ Sn=(n/2)[2a+(n−1)d].
⇒ S20 =(20/2)[2×48+(20−1)8].
⇒ S20 = (20/2)[96+152]
⇒ S20 = 10 × 248 = 2480.
∴ 2480 meters he run in bringing back all the potatoes.