JEE Main 2016 · 3 Apr · Shift 1 · Mathematics Q68

MathematicsSingle correct+4 / -1Question 68 of 90

If the 2 $^{\text{nd}}$ , 5 $^{\text{th}}$ and 9 $^{\text{th}}$ terms of a non-constant A.P. are in G.P., then the common ratio of this G.P. is :

\dfrac85

\dfrac43

\dfrac74

Answer and worked solution

Official answer: B

$(a+4d)^2=(a+d)(a+8d)$ gives $8d^2=ad$ , so $a=8d$ . The terms are $9d,12d,16d$ , with ratio $\frac43$ .

JEE Main 2016 · 3 Apr · Shift 1, Mathematics question 68