Question

1 day = 2 rupees, 2 day = 4 rupees, 3 days = 8 rupees, 4 days = 16 rupees, 10 days = 1023 rupees so 30 days = how many rupees ?

Answer 1

Answer:

Surendra's savings are Rs. 1, Rs. 2, Rs. 3,.... which is an A.P.

Here, t

1

=1, n=20

t

n

=t

20

=20; S

n

=S

20

=?

Therefore, S

n

=

2

n

(t

1

+t

n

)

⇒S

20

=

2

20

(1+20)

⇒S

20

=

2

20

×21=210

Hence, Surendra's total savings after 20 days will be Rs. 210.