Q12 of 31 Page 1

In an AP, the sum of first n terms is . Find the 25th term.

Given


Sum of n terms of AP,


25th term of an AP = Sum of 25 terms – Sum of 24 terms


⇒ a25 = S25 – S24





⇒ a25 = 1100 – 1020 = 80


Therefore, 25th term of given AP is 80.


More from this chapter

All 31 →
10

Find the number of coins of 1.5 cm diameter and 0.2 cm thickness to be melted to form a right circular cylinder of height 10 cm and diameter 4.5 cm.

 11

Solve , a+b ≠ 0

 13

The ninth term of an AP is equal to seven times the second term and twelfth term exceeds five times the third term by 2. Find the first term and the common difference.

 14

In the given figure, the radii of two concentric circles are 13 cm and 8 cm. AB is diameter of the bigger circle. BD is the tangent to the smaller circle touching it at D. Find the length AD.