One side of the bottom layer of a triangular pyramid has 12
balls. How many are there in the whole pyramid?

Note that the pyramid is equilateral and solid.

Answers were Sorted based on User's Feedback



One side of the bottom layer of a triangular pyramid has 12 balls. How many are there in the whole ..

Answer / keyur

I think there are 78 Balls..
At bottom Layer has 12 balls.Above that 11 balls are there.
In this Way 12,11,10,9,8,7,6,5,4,3,2,1.
So tptal balls are 78..

Is This Answer Correct ?    8 Yes 4 No

One side of the bottom layer of a triangular pyramid has 12 balls. How many are there in the whole ..

Answer / guest

There are total 364 balls.

As there are 12 balls along one side, it means that there
are 12 layers of balls. The top most layer has 1 ball. The
second layer has 3 (1+2) balls. The third layer has 6
(1+2+3) balls. The fourth layer has 10 (1+2+3+4) balls. The
fifth layer has 15 (1+2+3+4+5) balls. Similarly, there are
21, 28, 36, 45, 55, 66 and 78 balls in the remaining layers.

Hence, the total number of balls are

= 1 + 3 + 6 + 10 + 15 + 21 + 28 + 36 + 45 + 55 + 66 + 78

= 364 balls

Is This Answer Correct ?    11 Yes 8 No

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