Question 43

waecmaths question: 

The fourth term of an Arithmetic progression (A.P) is 37 and the first term is −20. Find the common difference

Option A: 

63

Option B: 

57

Option C: 

19

Option D: 

17

waecmaths solution: 

$\begin{align}  & a=-20,\text{ }{{T}_{4}}=37 \\ & {{T}_{n}}=a+(n-1)d \\ & {{T}_{4}}=a+(4-1)d=a+3d \\ & {{T}_{4}}=a+3d \\ & 37=-20+3d \\ & 3d=57 \\ & d=\frac{57}{3}=19 \\ & \text{The common difference is 19} \\\end{align}$

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