Further Mathematics Paper 2 WASSCE private candidates second series 2019

Question 2

The fourth and sixth terms of a Geometric Progression (G.P.) are 54 and 486 respectively.


If r > 0, find the third term.



Observation

The Chief Examiner reported that majority of the candidates that attempted this question did

well.

They were able to express the

third term as

𝑎r3 = 54------------- (1)

and sixth term as

𝑎𝑟 5 = 486 ----------- (2).

Dividing equations (2) by (1), 𝑟2= 486 54 = 9 and this yielded r = 3.

They substituted for in equation (1) and solved for the first term and obtained a = 2.


Then, the third term is 2×32 = 18.