Question

RUSH PLEASE

A grocer has a triangular display of oranges in a window. There are 14 oranges in the bottom row and the number of oranges decreases by one in each row above this row. How many oranges are in the display?

Answer 1

There are 14 oranges in bottom row, 13 in next , 12 in next and so on....
So total oranges are sum of (14+13+12+.......+3+2+1)
which is sum of first n natural numbers given by n*(n+1)/2
therefore sum of 1 to 14 is 14 * 15 /2
which is 105
Therefore there are 105 ornanges.