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Question
How many multiples of 4 lie between 10 and 250?
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Solution
Numbers between 10 and 250 which are multiple of 4 are as follows:
12, 16, 20, 24, ........., 248
Clearly this forms an A.P. with first term a = 12,
Common difference d = 4 and last term I = 248
⇒ 248 = 12 + (n – 1)(4)
⇒ 248 = 12 + 4n – 4
⇒ 248 = 4n + 8
⇒ 4n = 248 – 8
⇒ 4n = 240
⇒ n = `240/4`
⇒ n = 60
Thus, 60 multiples of 4 lie between 10 and 250.
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