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All the terms of an AP are natural numbers and the sum of the first 20 terms is greater than 1072 and lss than 1162.If the sixth term is 32, thenA. first term is 7B. first term is 12C. common difference is 4D. common difference is 5

Answer» Correct Answer - A::D
Let the AP start with n and common differencem, then according to question,
`n+5d=32`
`n=32-5d " " "…..(i)"`
and `1072ltn+(n+d)+"……."+(n+19d)lt1162`
`1072lt20n+(19xx20)/(2)dlt1162`
`1072lt640-100d+190dlt1162`
`432lt90dlt522`
`4.8ltdlt5.8`
Let d is natutal number, so `d=5`
`:.n=32-5xx5=7`
First term is 7 and common difference is 5.


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