Railway RRB / NTPC — Mathematics
NTPC, Group D, JE — all sections
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in Mathematics
A mixture contains milk and water in the ratio 5:3. If there are 40 liters of milk, how much water is there?
Correct Answer:
B. 24 liters
EXPLANATION
If milk is 5 parts and equals 40L, then 1 part = 8L; water (3 parts) = 24L
The average of five numbers is 22. If four of them are 18, 24, 20, and 26, what is the fifth number?
Correct Answer:
B. 22
EXPLANATION
Sum = 22 × 5 = 110; 18 + 24 + 20 + 26 = 88; Fifth = 110 - 88 = 22
If a number is increased by 15% and the result is 345, what was the original number?
Correct Answer:
B. 300
EXPLANATION
x × 1.15 = 345; x = 345/1.15 = 300
What is 20% of 35% of 2000?
Correct Answer:
B. 140
EXPLANATION
35% of 2000 = 700; 20% of 700 = 140
A train leaves Station A at 8:00 AM and reaches Station B at 2:30 PM. If the distance is 195 km, what is the average speed?
Correct Answer:
B. 30 km/h
EXPLANATION
Time = 6.5 hours; Speed = 195/6.5 = 30 km/h
What is the simple interest on Rs. 5000 at 8% per annum for 3 years?
Correct Answer:
B. Rs. 1200
EXPLANATION
SI = (P × R × T)/100 = (5000 × 8 × 3)/100 = 1200
Two numbers are in the ratio 3:5. If their sum is 80, what are the numbers?
Correct Answer:
B. 30 and 50
EXPLANATION
3x + 5x = 80; 8x = 80; x = 10. Numbers are 30 and 50
A shopkeeper sells an item for Rs. 600 and makes a profit of 25%. What was the cost price?
Correct Answer:
B. Rs. 480
EXPLANATION
If profit is 25%, then SP = CP × 1.25; 600 = CP × 1.25; CP = 480
What is the LCM of 12 and 18?
Correct Answer:
B. 36
EXPLANATION
LCM of 12 and 18 = 36