Question

An AP consists of 50 terms of which 3rd term is 12 and the last term is 106 find the sum of 25 terms.​

Answer 1

GIVEN

• 3rd term = 12
• last term = 106
• Number of Total Term = 50

SOLUTION ✍️

• a + 2d = 12 _(i)

• a + 49d = 106 _(ii)

Solving above eqn, we get

• 47d = 94

• d = 2

• a + 4 = 12

• a = 8

25th term

• = a + 24d

• = 8 + 48

• = 56

$\begin{gathered}\\\\\end{gathered}$

Answer 2

Answer:

GIVEN

3rd term = 12

last term = 106

Number of Total Term = 50

SOLUTION ✍️

a + 2d = 12 _(i)

a + 49d = 106 _(ii)

Solving above eqn, we get

47d = 94

d = 2

a + 4 = 12

a = 8

25th term

= a + 24d

= 8 + 48

= 56

$\begin{gathered}\\\\\end{gathered}$