Question

a man saved Rupees 50 in first month, rupees 80 second month, rupees 110 in the third month and so on .how much he save in 5 years?

Answer 1

Money saved in 1st,4th,7th and 10th month) = 50 X 4 =     200
Money saved in 2nd,5th , 8thand 11th month) = 80 X 4 =   320
Money saved in 3rd, 6th, 9th and 12th month) = 110 X 4 = 440
Total in 1 year = 960
in 5 years = 5 X 960 = 4800

Answer 2

Step-by-step explanation:

Ans.

The given series is 50 + 80 + 110 + .......

So, a = 50, d= 30

or, n = 5 years = 5 x 12 = 60 months.

:: Sn = {2a + (n - 1) d}

= 60 (2 x 50 + (60 - 1) 30)

= 30 {100 + 59 x 30

= 30 {100 + 1,770)

= 30 (1,870} = 56,100 Rs.