1.) steamer goes downstream from one port to another in 6 hours it cover the same distance upstream in 7 hours if the speed of the stream be to km per hour find the speed of the steamer in still water.
2.) 2 years ago father was three times as old as his son and two years hence twice his age will be equal to 5 times that of his son find their present age.
Answers
Answer:
answer 1.) 26km/hr
explanation
let the speed of the streamer in still water be X km per hour
speed of stream 2 km per hour
it is given that while going downstream the streamer takes 6 hours to cover the distance between two ports.
therefore speed of stream and downstream is
(x+2)km/hr
distance covered in one hour (x+2)km
distance covered in 6 hours = 6(x+2)km
therefore distance between two ports=6(x+2)km
it is given that while going upstream the streamer takes 7 hours to cover the distance
speed of streamer upstream (x-2)km/hr
distance covered in one hour (x-2)km/hr
distance covered in 7 hours 7(x-2)km/hr
distance between two ports in this case 7(x-2)km/hr
the distance between two ports is the same
from 1 and 2 we get
6(x+2) = 7(x-2)
6x + 12 = 7x - 14
6x - 7x = -14 -12
-x = -26
minus minus cancel out
x = 26 .
answer 2.) son = 14 , father = 38
2 years ago
son's age be x
father's age 3x
two years hence / later
son's age = x+4
father's age= 3x + 4
therefore , 2(3x + 4) = 5(x + 4)
6x + 8 = 5x + 20
6x - 5x = 20-8
x = 12
present age of son = 12+2=14yrs
present age of father =(3×12)+2 = 38