Question

find the sum of all 2 digit numbers greater
than 50 which when divided by 7 Leaves remainder
4.​

Answer 1

Step-by-step explanation:

The 2-digit number which when divided by 7 gives remainder 4 are: 53,60.. 95.

Here a = 53, d = 60 - 53 = 7, tn = 95.

nth term of an AP is tn = a + (n – 1) * d

=> 95 = 53 + (n – 1) * 7

⇒ 95 = 53 + 7n - 7

⇒ 95 = 46 + 7n

=> n = 7

Now,

Recall Sum of n terms of AP:

Sn = (n/2)[2a + (n - 1) * d]

S₇ = (7/2)[106 + 42]

    = 518

Hope this helps!