Govt. Exams
Entrance Exams
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Topics in Railway RRB / NTPC
A sum of money becomes Rs. 1800 in 2 years and Rs. 2100 in 4 years at simple interest. What is the principal?
Correct Answer:
C. Rs. 1500
EXPLANATION
Interest in 2 years = A₂ - A₄/2 = 1800 - 1050 = 750; Interest per year = 375; Principal = 1800 - 750 = 1500
Two pipes can fill a tank in 12 hours and 15 hours respectively. If both are opened together, in how many hours will the tank be filled?
Correct Answer:
A. 6.67 hours
EXPLANATION
Work rate = 1/12 + 1/15 = 5/60 + 4/60 = 9/60 = 3/20; Time = 20/3 ≈ 6.67 hours
A discount of 10% is given on an item, and then another 15% discount is applied. What is the overall discount percentage?
Correct Answer:
C. 23.5%
EXPLANATION
After 10% discount: 90%; After 15% on 90%: 90% × 85% = 76.5%; Overall discount = 23.5%
If x² - 5x + 6 = 0, what are the values of x?
Correct Answer:
A. 2 and 3
EXPLANATION
x² - 5x + 6 = (x-2)(x-3) = 0; x = 2 or x = 3
A person travels 60 km by train at 40 km/h and 30 km by bus at 30 km/h. What is the average speed for the entire journey?
Correct Answer:
C. 36 km/h
EXPLANATION
Time by train = 1.5 h; Time by bus = 1 h; Total distance = 90 km; Total time = 2.5 h; Average = 90/2.5 = 36 km/h
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
