Answer:
Step-by-step explanation:
The data of timing for each lap will form a arthmetic progression ( AP ) with first term as 25 s and common difference of 1.6 s .
a )
first term a = 25
common difference d = 1.6 .
10 th term of the series can be given by following formula
a₁₀ = 25 + ( 10-1 ) x 1.6
= 25 + 1.6 x 9
= 39.4 s
b )
Let n th be the last lap
a(n) = a + ( n-1 ) x d
55.4 = 25 + ( n- 1 ) x 1.6
n - 1 = 19
n = 20 .
c )
sum of all the term of AP
=( first term + last term ) x no of term / 2
= (25 + 55.4 ) x 20 / 2
= 804 s .
= 804 / 60 min
= 13.4 min .
