1.

Solve this problem question no.4

Answer»

T19 = 52

=> a + 18d = 52 -------(1)

T38 = 128

=> a + 37d = 128 -------(2)

On subtracting equation 1 from 2, we get

19d = 76

=> d = 4

Now,

a + 18(4) = 52

=> a + 72 = 52

=> a = 52 - 72

=> a = - 20

S56 = 56 /2 [ 2(-20) + ( 55)(4)]

= 28 ×( - 40 + 220)

= 28 × 180

= 5040


Discussion

No Comment Found

Related InterviewSolutions