Question

Look at the pyramid. The pair of adjacent cells in the bottom row add up to give the number in the corresponding top cell in the next row; and these two cells add upto give the number at the top of the pyramid. What are the three consecutive numbers, we should start with, to get 300 at the top of the pyramid?

• A. 24, 25, 26
• B. 149, 150, 151
• C. 74, 75, 76
• D. 99, 100, 101

Answer 1

The correct option is C

74, 75, 76

Let three consecutive number in the bottom row be $x$, $x+1$ and $x+2$.

Adding adjacent cells in the bottom row, we get

$\left(x\right)+(x+1)=2x+1$ …………..(1)

Similarly,

$(x+1)+(x+2)=2x+3$ ………… (2)

Adding (1) and (2) for the top most cell we get:

$(2x+1)+(2x+3)$

$=4x+4$

Now we know that,

$4x+4=300$

$4x=300-4$

$4x=296$

$x=296÷4=74$

$x+1=74+1=75$

$x+2=74+2=76$

Thus, the three consecutive numbers are 74, 75 and 76.