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Xavier Aptitude Test 2019 Paper

Question : 60 of 98

Marks: +1, -0

Solution:

Total number of apples

=1+2+3+4+\dots+n

=\frac{n(n+1)}{2}

Now,

\frac{n+(n+1)}{2} \leq 150

\Rightarrow n (n+1) \leq 350

lf n = 16, then

n (n+1) = 16 \times 17

= 272 \leq 350

If n = 16, then n (n +1) = 17 × 18 = 306 > 350

Hence, in the fruit shop, apples are initially in 16 rows.

Total number of apples initially

=\frac{16\times 17}{2}=136

Now,

136-126 = 10

And

1+2+3+4=10

Hence, apples in the top 4 rows had sold, when 126 apples remained in the shop.

∴ Total number of rows having 126 apples left

=16-4=12

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