Sequence And Series
Balls are arranged in a row to form an equilateral triangle. The first row consist of one ball , the second row of two balls , the third row of three balls and so on. If 669 more balls are added then all the balls can be arranged in the shape of a square and each of the sides, then contains 8 balls less than each side of the triangle, then the initial numbers of balls must be n. What is the value of n/10?
The answer is 154.
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1 solution
let X number of ball makes one side of triangle, so total number of balls in triangle will be X (X+1)/2.now side of square has 8 balls less than triangle means (X-8) and so total balls in square will be (X-8)^2. so nw eqn frms like[ X (X+1)/2]+669=(X-8)^2 you will get X=55 now find total no. of balls in triangle which is 1540 and then divide it by 10..=154.