Paper 1 · Mathematical Reasoning and Aptitude
UGC NET June 2023 (20.06.2023) Shift-I
A certain sum of money becomes Rs 1000 in 2 years and Rs 1100 in 4 years at a simple rate of interest. The rate of interest per annum is
A4 and 3 by 7 percent
B5 and 5 by 9 percent ✓ Correct
C7 and 4 by 7 percent
D6 and 4 by 9 percent
Correct answer: (B) 5 and 5 by 9 percent — The rate is 5 and 5 by 9 percent, so the answer is 5 and 5 by 9 percent.
Explanation
★The rate is 5 and 5 by 9 percent, so the answer is 5 and 5 by 9 percent.
★The amount grows from 1000 at 2 years to 1100 at 4 years.
★So the simple interest for the 2 years in between is 100.
★At simple interest each year adds the same amount, so 2 years of interest is 100, giving 50 per year.
★Over the first 2 years the interest is also 100, so the principal is 1000 minus 100, which is 900.
★The yearly interest of 50 on a principal of 900 gives a rate of 50 over 900 times 100.
★That equals 5 and 5 by 9 percent per annum.
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