Discussion of Question with ID = 030 under Problems-on-Numbers

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Question

How many odd numbers are there between -1570 and 2426?

A

1998.

B

1999.

C

1997.

D

2000.

Soln.
Ans: a

Odd numbers are in an AP. First term $a = -1569$, common difference $d = 2$, the last term $t_n$ is given as 2425. By the AP formula, $2425 = -1569 + (n - 1) × 2$ ⇒ $n = 1 + {{2425 - (-1569)}/2} = 1998$.


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