UP Police Constable Exam Model Paper 1

Given -
–4 – 1 + 2 + 5 + ……….
Formula used -
for an arithmetic progression, ${\mathrm{n}}^{\mathrm{th}}$ term formula
${\mathrm{T}}_{\mathrm{n}}=\mathrm{a}+\left(\mathrm{n}-1\right)\times \mathrm{d}$
where, a = first term, n = number of term, d = common difference
Solution -
Let the 10${}^{\mathrm{th}}$ term be ${\mathrm{T}}_{10}$.
–4 – 1 + 2 + 5 + ……….
⇒ a = - 4, n = 10, d = (- 1 + 4) = 3
⇒ ${\mathrm{T}}_{10}=-4+\left(10-1\right)\times 3$
⇒ ${\mathrm{T}}_{10}=23$
∴ 10${}^{\mathrm{th}}$ term of progression = 23.