Question

please help class 10 arithmetic progression​

Answer 1

The last Term (aₙ) = 98000

The First Term (a₁) = 1000

Common Difference (d) = 100

(i) We can form an A.P since we have the first term which is 1000 and to get the other terms we keep adding 100 and then we know that the last term is 9800. so

A.P = 1000, 1100, 1200...98000

Now we need to find the 30th term, we can use the formula aₙ = (a₁ + (n - 1) d). Here the 30th term is aₙ and n is 30 since we need the 30th term so let's find it

aₙ = (a₁ + (n - 1) d)

   = (1000 + (30 - 1) 100)

   = (1000 + (29) 100)

   = (1000 + 2900)

 = 3900

So the amount on the 30th  is 3900

(ii) So here we need to find which term is 98000. So we can use the same formula here instead of finding aₙ, we have to find n since we already have aₙ as 98000.

aₙ = (a₁ + (n - 1) d)

98000 = (1000 + (n - 1) 100)

98000 = 1000 + 100n - 100

98000 = 900 + 100n

98000 - 900 = 100n

97100 = 100n

97100/100 = n

971 = n

n = 971