1.

The 13th term of an AP is 4 times its 3rd term. If its 5th term is 16 then the sum of its first ten terms isA. 150B. 175C. 160D. 135

Answer» Correct Answer - B
`T_(13) = 4 xx T_(3) rArr a+12d = 4(a+2d) rArr 3a-4d = 0 " "…(i)`
`T_(5) = 16 rArr a +4d = 16 " ".. (ii)`
On solving (i) and (ii), we get a = 4 and d= 3
`S_(10) = (10)/(2)(2a +9d) = 5(2 xx 4 +9 xx 3) = 175`


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