Tanvika purchases every year National Saving Certificates of value exceeding the last year purchases by Rs. 25. After 20 years, he find the total value of certificates purchased by him is Rs. 7250. Find the value of the certificates purchased.
(i) in the first year. (ii) in the 12th year.
⇒ 7250 = 10 (2a + 475)
⇒ 725 = 2a + 475 ⇒ 2a = 250
⇒ a = 125
Hence, the value of certificates purchased in first year = Rs. 125.
Now, value of certificates purchased in 12th year.
a12 = a + (12 – 1 )d = 125 + (11) (25) = 125 + 275 = Rs. 400.