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Find the sum of first 20 terms of an A.P...

Find the sum of first 20 terms of an A.P., in which `3r d` terms in 7 and `7t h` term is tow more than thrice of its `3r d` term.

A

740

B

840

C

920

D

680

Text Solution

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The correct Answer is:
A
the sum of first 20 terms of an A.P., in which `3r d`

terms in 7 and `7t h`

term is tow more than thrice of its `3r d` term.

Hence the sum of first 20 terms is 740.

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