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In arithmetic progression(A.P.), the first term is 7 and the 6th term is 22. The sum of the first 10 terms of A.P. is:

Solution

✅ Correct Option: 2

The first term is a1=7a_1 = 7 and the 6th term is a6=22a_6 = 22.

The general term of an arithmetic progression is:

an=a1+(n−1)×da_n = a_1 + (n - 1) \times d

For the 6th term:

a6=a1+(6−1)×da_6 = a_1 + (6 - 1) \times d

22=7+5d22 = 7 + 5d

15=5d15 = 5d

d=3d = 3


The sum of the first nn terms of an arithmetic progression is:

Sn=n2×[2a1+(n−1)×d]S_n = \frac{n}{2} \times [2a_1 + (n - 1) \times d]

For the first 10 terms with a1=7a_1 = 7 and d=3d = 3:

S10=102×[2(7)+(10−1)×3]S_{10} = \frac{10}{2} \times [2(7) + (10 - 1) \times 3]

S10=5×[14+9×3]S_{10} = 5 \times [14 + 9 \times 3]

S10=5×[14+27]S_{10} = 5 \times [14 + 27]

S10=5×41S_{10} = 5 \times 41

S10=205S_{10} = 205

Therefore, the sum of the first 10 terms is 205205.

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