Question

If on his 1st birthday ₹100 on his 2 birthday ₹300 then on his 15 birtday ₹?

Answer 1

The given condition is in arithmetic progression,

a(1)=100

a(2)=200

We must find for a(15)

By an formula we have

an= a+(n-1)d

d(common difference) =a(2)-a(1)

d=200-100

d=100

And a=100

Now n=15

a(15)=100+(15-1)100

a(15)=100+(14)100

a(15)=100+1400=1500

So on his 15 birthday he will get rupees 1,500