Question

There are 10 boxes on a table.Ramu places 4 marbles in 1st box,7 marbles,10 marbles in 3rd box and so on .Find the total number of marbles placed in all the boxes

Answer 1

Here he puts 4 marbles in first box and he increased 3 marbles in each box. So, here the AP is formed = 4,7,10, ........

First term= a = 4

Common difference = d =3

No. of terms = n = 10

We have to find sum of of an AP or we can say total no. of marble in ten box .

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

= 10/2 [ 2×4+ ( 10 - 1 ) 3 ]

= 5 [ 8 + (9) 3 ]

= 5 [ 8 + 18 ]

= 5 [ 26 ]

= 130

Answer = 130 marbles

Answer 2

Answer:

ans is 175...check it out...