Central Exam — Railway RRB / NTPC — Mathematics
UPSC · SSC · Bank · Railway · NDA — Central Government Exam MCQ Practice
Showing 1–5 of 5 questions
in Mathematics
Q.1
Hard
Mathematics
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
Q.2
Hard
Mathematics
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
Q.3
Hard
Mathematics
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%
Q.4
Hard
Mathematics
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
Q.5
Hard
Mathematics
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