SOLVED PAPER 2021 (CDS) (II) (Elementary Mathematics)

Total Questions: 100

91. If the system of equations 7x + ky = 27 and kx + 7y = 19 have unique solution, then which one of the following is correct

Correct Answer: (a) k ≠ 7
Solution:

92. A sum of money compounded annually doubles itself in 5 year. In how many years will it become four times of itself?

Correct Answer: (a) 10 years
Solution:

93. Between 3 and 4 O'clock, both hour hand and minute hand will coincide past 3 O'clock between

Correct Answer: (b) 16-17 min
Solution:

94. Sheela can stitch a suit in 2 days, while Meena can stitch a suit in 1½ days. How many days will both take in stitching 30 suits?

Correct Answer: (c) 35 days
Solution:


95. If 2x - 3y - 7 = 0 then what is the value of 8x³ - 36x²y + 54xy² - 27y³ - 340 ?

Correct Answer: (d) 3
Solution:

96. If p varies directly as q and inversely as square of r, what is the percentage increase in p due to an increase in q by 20% and a decrease in r by 20% ?

Correct Answer: (a) 87.5%
Solution:

97. A person agrees to work for 30 days, on a condition that for every day's work he should receive ₹500, and that for every day's absence from work he should forfeit ₹100. At the end of the time he received ₹11,400. How many days did he work?

Correct Answer: (c) 24
Solution:


98. A person bought a chair and a table for ₹750. He sold the chair at a gain of 5% and the table at a gain of 20%. he gained 16% on the whole. What is original cost of table?

Correct Answer: (c) ₹550
Solution:


99. A person rode one third of a journey at 60 km/hr, one third at 50 km/hr and the rest at 40 km/hr. Had the person ridden half of the journey at 60 km/hr and the rest at 40 km/hr, he would have taken 4 minutes longer to complete the journey. What distance did the person ride?

Correct Answer: (c) 240 km
Solution:



100. A person saves ₹100 more than he did the previous year. If he saves ₹2000 in the first year, in how many years will he save ₹170000.

Correct Answer: (b) 17 year
Solution: