Rationale: Speed downstream = 60 + 20 = 80 kmph
Speed upstream = 60 - 20 = 40 kmph
The answer: (B)
Question: The speed of a boat in still water is 60kmph and the speed of the current is 20kmph. Find the speed downstream and upstream?
Options:
(A) 35, 25 kmph
(B) 80, 40 kmph
(C) 40, 60 kmph
(D) 50, 55 kmph
(E) 50, 65 kmph
Reasoning: 1 to 9 = 9 * 9 = 81
1 to 5 = 5 * 10 = 50
5 to 9 = 5 * 8 = 40
5th = 50 + 40 = 90 81 = 9
Ans: (A)
Question: The average of 9 observations was 9, that of the 1st of 5 being 10 and that of the last 5 being 8. What was the 5th observation?
Options:
(A) 9
(B) 8
(C) 7
(D) 6
(E) 5
Rationale: The total of seven numbers = 7X26 = 182
The total of first 3 and last 3 numbers is = 3 X 14+3 X 19 = 99
So, the middle number is (182 - 99 ) = 83
The answer: (B)
Question: The average of seven numbers is 26. The average of first three numbers is 14 and the average of last three numbers is 19. What is the middle number?
Options:
(A) 25
(B) 83
(C) 29
(D) 32
(E) 34
Reasoning: S = 180/6 * 18/5 = 108 kmph
Ans: (B)
Question: A 180 meter long train crosses a man standing on the platform in 6 sec. What is the speed of the train?
Options:
(A) 228
(B) 108
(C) 1266
(D) 188
(E) 211
Rationale: T = 500/100 = 10 h
T = 10 - 4 = 6
Time Ratio = 10:6 = 5:3
Speed Ratio = 3:5
The answer: (C)
Question: A motorcyclist goes from Nagpur to Pune, a distance of 500 kms at an average of 100 kmph speed. Another man starts from Nagpur by car 3 hours after the first, and reaches Pune hour earlier. What is the ratio of the speed of the motorcycle and the car?
Options:
(A) 1:2
(B) 1:7
(C) 3:5
(D) 1:5
(E) 1:1
Rationale: Circumference C is given by
C = 2r = 2*10 = 20 cm
The answer: (A)
Question: Calculate the circumference of a circular field whose radius is 10 centimeters.
Options:
(A) 20 cm
(B) 19 cm
(C) 28 cm
(D) 25 cm
(E) 30 cm