Quantitative Aptitude

Sample Paper 10

Explanation:

Question 1: A beats B by 10 m means when A covers 100 m, then B covers 90 m

B beats C by 20 m means when B covers 100 m, then C covers 80 m.

So, when B covers 90 m, then C covers 80 ÷ 100 × 90 = 72 m

So, when A covers 100 m, then B covers 90 m and C covers 72 m

So, A beats C by 100 – 72 = 28 m

Question 2: Total surface area of pyramid = (1/2) P × l + B

Where; P is perimeter of base, l is slant height and B is area of base

Perimeter of base = 4 × 4 = 16 cm

Area of base = 4² = 16 sq cm

So, total surface area = (1/2) × 16 × 6 + 16

= 48 + 16 = 64 sq cm

Question 3: If the difference between sum of numbers at odd places and sum of numbers at even places of a number is either zero or divisible by 11 then the number is divisible by 11.

For 588885:

Sum of numbers at odd places = 5 + 8 + 8 = 21

Sum of numbers at even places = 8 + 8 + 5 = 21

Difference between sums = 21 – 21 = 0

So, 588885 is divisible by 11

Question 4: As a woman works half fast as a man so 6 women would complete the work in 2 × 10 = 20 days

So, time taken by 10 women = 6 × 20 ÷ 10 = 12 days

Question 5: As the sum is zero so sum of two groups of number would be equal but of opposite signs, i.e. positive and negative numbers.

Number of terms = 51

So, sum of 25 terms = negative of sum of another group of 25 terms

The middle term, i.e 26th term = zero

Question 6: This is a rule of thumb that money becomes double at 10% per annum compounded annually.

You can cross check this by applying the formula for compound interest:

If principal = 100

Then A = 100 × ((1+10)/(100))⁷

= 100 × (11/10)⁷

= 100 × 1.9487 = 200 (approx.)

Question 7: Possible number of ways = 6 × 5 × 4 × 3 = 360

First person can be seated in 6 ways, 2nd person in 5 ways, 3rd person in 4 ways and 4th person can be seated in 3 ways.

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