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A man accepts a position with an initial salary of Rs 5200 per month. It is understood that he will receive an automatic increase of Rs 320 in the very next month and each month there

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प्रश्न

A man accepts a position with an initial salary of Rs 5200 per month. It is understood that he will receive an automatic increase of Rs 320 in the very next month and each month thereafter. What is his total earnings during the first year?

योग
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उत्तर

Given that fixed increment in the salary of a man

= Rs. 320 each month

Initial salary = Rs. 5200 which makes an A.P.

whose first term (a) = Rs. 5200 and common difference (d) = Rs. 320

Total earning during the first year (12 months)

S12 = `12/2 [2 xx 5200 + (12 - 1) xx 320]`  .....`[because "S"_n = n/2 [2a + (n - 1)"d"]]`

= 6[10400 + 3520]

= 6 × 13920

= Rs. 83520

Hence, the required amount is Rs. 83520

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अध्याय 9: Sequences and Series - Exercise [पृष्ठ १६१]

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एनसीईआरटी एक्झांप्लर Mathematics Exemplar [English] Class 11
अध्याय 9 Sequences and Series
Exercise | Q 3.(ii) | पृष्ठ १६१

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