20128.The present age of a father is 3 years more than three times the age of his son.Three years hence,father as age will be 10 years more than twice the age of the son.Find the present age of the father.
23 years
30 years
33 years
42 years
Explanation:
Let the present age be `x` years. Then father`s present age is 3x+3 years. Three years hence (3x+3)+3=2(x+3)+10 x=10 Hence father`s present age = 3x+3 =[ (3 x 10) + 3] = 33 years.
20129.In one hour a boat goes 11 km long the stream and 5 km against the stream.The speed of the boat in still water is?
8 kmph
7 kmph
8.5 kmph
9 kmph
Explanation:
Speed in still water A =1/2 ( 11+5) km/hr A= 8 kmph
20130.A train 110 m long travels at 60 kmph. How long does it take to pass a telegraph post by the side of the track ?
5.6 seconds
6.5 seconds
6.6 seconds
6.7 seconds
Explanation:
Speed of train = 60 × 5/18 m/s = 50/3 m/s => Time taken to cross the telegraph post = 110/(50/3) = 6.6 seconds
20131.The average ages of three persons is 27 years. Their ages are in the proportion of 1:3:5. What is the age in years of the youngest one among them ?
8
6
7
9
Explanation:
Let the age of three persons be x, 3x and 5x => 9x/3 = 27 = > x = 9
20132.The greatest number of four digits which is divisible by 15, 25, 40 and 75 is:
9000
9400
9600
9800
Explanation:
Greatest number of 4-digits is 9999. L.C.M. of 15, 25, 40 and 75 is 600. On dividing 9999 by 600, the remainder is 399. Required number (9999 - 399) = 9600.