The product of a two-digit number and a number consisting of the same digits written in the reverse order is equal to 2,430. Find the numbers.
45, 54
65, 56
52, 25
None of these
Answer: Option A.
1st is the correct answer because 45 54 = 2430.
There is a natural number which becomes equal to the square of a natural number when 100 is added to it, and to the square of another natural number when 168 is added to it. Find the number.
189
69
156
224
Answer: Option C.
. 3rd option is correct because 100 + 156 = 256 (square of 16)
and 168 + 156 = 324 (square of 18).
A and B are two stations 1000 km. A train starts from A at 70 km/h and another train starts from B at same time at the rate of 30 km/h. How far from A will they cross each other?
700 km.
300 km
70 km
200 km
None of these
Answer: Option A.
Total distance = 1000 km, Relative speed = 70 + 30 = 100 km/h.
Time after which the train will meet.1000/100 -10hours.
In 10 hour train A will cover distance = 70 * 10 = 700 km.
Two cyclist A and B starts from same place at the same time, one going towards east at a rate of 20 km /h and another towards west at a rate of 10 km/h what time will they take to be 75 km apart.
3 hour
2.5 Hours
2 Hours
3.25 Hours
None of these
Answer: Option B.
Relative speed = 20+10 = 30 km/h, Distance to be covered = 75 km Time taken to cover that distance = 75/30 = 5/2 hour = 2.5 hour.
A person covers half of his journey at 30 km/hr and the remaining half at 20 km/hr. The average speed for the whole journey is
A person covers a certain distance by travelling at a uniform speed of 120 km/h for 90 minutes. At what speed will he have to travel in order to cover the same distance in 1 hour 20 minutes? (in km/h)
135
125
140
130
145
Answer: Option A.
Distance = 120 × 90/60 = 180 km
Speed required to cover 180 km in 1 hr 20 mins
( 4/3 hrs) = 180 × ¾ = 135 km/hr
In Jar A, 120 litres milk was mixed with 24 litre water. 12 litre of this mixture was taken out and 3 litre water was added. If 27 litre of newly formed mixture is taken out, what will be the resultant quantity of water in the jar? (In litre)
20
10
15
30
25
Answer: Option A.
Ratio of milk : water in Jar A = 120 : 24 = 5 : 1
12 lts of this mixture is taken out => milk = 5/6 × 12 = 10
lts and water = 2 lts taken out
3 lts of water added = 24 – 2 + 3 = 25
lts => new ratio of milk : water = 110 : 25 = 22 : 5
Now 27 lts of this mixture is again taken out
=> water taken out = 5/27 × 27 = 5 lts water left = 25 – 5 = 20 lts
A boat, whose speed in 15 km/hr in still water goes 30 km downstream and comes back in a total of 4 hours 30 minutes. What is the speed of the stream? (in km/hr)
10
6
5
4
15
Answer: Option C
Speed of boat = 15 k/h
Let the speed of stream be ‘S’
Given : 30/(15+S) + 30/(15-S) = 9/2
Solving we get, S = 5 km/h
