# Quardratic equation

A motor boat whose speed is 18 km/hr in still water takes 1 hour more to go 24 km upstream than to return downstream to the same spot ,find the speed of strem.

A. 6 km/hr

B. 8 km/hr

C. 4 km/hr

D. NONE

[email_link] http://solvemaths.in/quardratic-equation/UncategorizedA motor boat whose speed is 18 km/hr in still water takes 1 hour more to go 24 km upstream than to return downstream to the same spot ,find the speed of strem.
A. 6 km/hr
B. 8 km/hr
C. 4 km/hr
D. NONE

dinesh
ppboomshankar@gmail.comSubscriberSOLVE - ΜΔΓΗŠ
Let the speed of the stream = x km/hr

Therefor,the speed of the boat upstream = (18-x) km/hr

the speed of the boat downstream= (18+x)km/hr

The time taken to go upstream = distance/speed

= 24/18-x hrs.

similarly, the time taken downstream = 24/18+x hrs.

According to the question,

24/18-x-24/18+x = 1

24(18-x)-24(18+x)= 1

24×18 + 24x -24×18 + 24x = (18-x)(18+x)

48x = 324 – x2

x2+48x – 324 =O

X= 6, -54

Hence , the speed of the stream = 6 km/hr

ANSWER= A. 6 km/hr