Question

a man saves rupees 600 in january. How much does he save during the whole year if every month he saves rupees 20 less than the previous month?​

Answer 1

Answer:5,880

Step-by-step explanation:

january:600

February:580

March:560

April:540

May:520

June:500

July:480

August:460

Sep:440

October:420

November:400

December:380

Total=5,880

Answer 2

Answer: 5880

Step-by-step explanation:

Here (n) number of terms =12 [as amount asking for the whole year; Whole year= 1 year=12 months]

(a) = ₹600 [as he saves ₹600 for the first year]

Difference (d)= ₹-20 [as he saves RS 20 less than previous year]

We know: Sn = n/2[2a+(n-1)*d]

Here:. S12= 12/2 [2*600 + (12-1)*(-20)]

= 6 [1200 + (11)*(-20)]

= 6 [1200 - 220]

= 6 [980]

= 5880

Hope this will help you.

Thnx ...........

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From:- Ankan_Saha