Correct Answer - Option 4 : 11
Given∶
Last team received $ 40,000.
Champion team received $ 65,000.
Award increases by $2500 for the successive finishing places.
Formula Used∶
nth term of A.P. = a + (n - 1)d
Calculation∶
Prizes received by the teams in increasing order are, $ 40,000, $ 42500, $ 4500, $47500,.........
This is an A.P. with a = 40,000, d = 2500 and l = 65,000
Let the number of terms be n. Then,
an = 65000
a + (n - 1)d = 65000
⇒ 40000 + (n - 1) × 2500 = 65000
⇒ (n - 1) × 2500 = 65000 - 40000
⇒ (n - 1) = 25000/2500
⇒ n - 1 = 10
⇒ n = 10 + 1 = 11
∴ 11 teams participated in Football World Cup.