Govt. Exams
Entrance Exams
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Topics in Quantitative Aptitude
What is the LCM of 12 and 18?
Correct Answer:
A. 36
EXPLANATION
Prime factorization: 12 = 2² × 3, 18 = 2 × 3². LCM = 2² × 3² = 4 × 9 = 36 (taking highest powers of all prime factors).
Find the HCF of 48 and 64.
Correct Answer:
B. 16
EXPLANATION
Using prime factorization: 48 = 2⁴ × 3, 64 = 2⁶. HCF = 2⁴ = 16 (taking lowest powers of common prime factors).
If a number is divisible by both 3 and 5, by which of these is it always divisible?
Correct Answer:
B. 15
EXPLANATION
If a number is divisible by both 3 and 5, and 3 and 5 are coprime (HCF=1), then the number must be divisible by their product: 3×5 = 15
What is the HCF (Highest Common Factor) of 48 and 64?
Correct Answer:
C. 16
EXPLANATION
Factors of 48: 1,2,3,4,6,8,12,16,24,48.
Factors of 64: 1,2,4,8,16,32,64.
Common factors: 1,2,4,8,16. HCF = 16
Find the smallest prime number greater than 20.
Correct Answer:
B. 23
EXPLANATION
Check: 21=3×7 (not prime), 23 is only divisible by 1 and 23 (prime), 25=5×5 (not prime), 27=3×9 (not prime).
So 23 is the smallest prime greater than 20.
What is the sum of the first 10 natural numbers?
Correct Answer:
B. 55
EXPLANATION
Sum of first n natural numbers = n(n+1)/2.
Here n=10, so sum = 10(11)/2 = 110/2 = 55
Arun invested some money at 14% simple interest for 5 years and earned ₹2800 as interest. If he had invested the same amount at 10% per annum for the same period, how much interest would he have earned?
Correct Answer:
B. ₹2000
EXPLANATION
Step 1: From first investment, 2800 = (P × 14 × 5) / 100 = 0.7P.
Step 2: P = 2800 / 0.7 = ₹4000.
Step 3: At 10% for 5 years, SI = (4000 × 10 × 5) / 100 = 200000 / 100 = ₹2000.
Priya invested ₹12000 at 8% simple interest per annum. In how many years will the interest earned be equal to the principal?
Correct Answer:
D. 12.5 years
EXPLANATION
Step 1: We need SI = P, so SI = ₹12000.
Step 2: Using SI = (P × R × T) / 100, we get 12000 = (12000 × 8 × T) / 100.
Step 3: 12000 = 960T, therefore T = 12000 / 960 = 12.5 years.
At what rate of simple interest per annum will ₹5000 amount to ₹6500 in 5 years?
Correct Answer:
B. 6%
EXPLANATION
Step 1: SI = Amount - Principal = 6500 - 5000 = ₹1500.
Step 2: Use SI = (P × R × T) / 100, so 1500 = (5000 × R × 5) / 100.
Step 3: 1500 = 250R, therefore R = 1500 / 250 = 6% per annum.
Rajesh borrowed ₹8000 from a bank at a simple interest rate of 6% per annum for 3 years. How much total amount will he have to repay?
Correct Answer:
A. ₹9440
EXPLANATION
Step 1: Use SI formula = (P × R × T) / 100.
Step 2: SI = (8000 × 6 × 3) / 100 = 144000 / 100 = ₹1440.
Step 3: Total Amount = Principal + SI = 8000 + 1440 = ₹9440.
