SOLUTION: Respected sir, 1] A distance is covered in 3 hours 48 min. at 5 kmph. how much time will be taken to cover it at 28.5 kmph ? 2] Ritu goes to school at 10 kmph & reaches the s

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Question 195410: Respected sir,
1] A distance is covered in 3 hours 48 min. at 5 kmph. how much time will be taken to cover it at 28.5 kmph ?
2] Ritu goes to school at 10 kmph & reaches the school 6 minutes late.Nwxt day, she covers this distance at 12 kmper hour & reaches the school 9 minutes eariler than the scheduled time.what is the distance of her school from her house ?
plz sir help me to solve this arith problem.
waiting for yurs reply.
take care
thank u.
Answer by ankor@dixie-net.com(22740) (Show Source):
You can put this solution on YOUR website!
1] A distance is covered in 3 hours 48 min. at 5 kmph. how much time will be taken to cover it at 28.5 kmph ?
:
Convert 3 hr 48 min to hrs; 3 + 48/60 = 3.8 hrs
:
we can use inverted ratio here, (Time varies inversely to speed)
let t = time to cover the dist at 28.5 km/hr
=
Cross multiply
28.5t = 5*3.8
:
28.5t = 19
t =
t = hr to cover that dist at 28.5 km
;
Check solution by finding the dist at each speed and time
.67 * 28.5 ~ 19 km
3.8 * 5 = 19 km
:
:
2] Rita goes to school at 10 kmph & reaches the school 6 minutes late.
Next day, she covers this distance at 12 km/hr & reaches the school 9
minutes earlier than the scheduled time.
What is the distance of her school from her house?
;
Let's just say the time difference between the two trips is 15 min, which hr
Write a time equation Time =
12 km time + hr = 10 km time
+ =
Multiply equation by 60 to get rid of the denominators, results:
5d + 15 = 6d
:
15 = 6d - 5d
d = 15 km is the distance
;
;
Check solution by finding the time of each trip
15/10 = 1.5 hr
15/12 = 1.25 hr
----------------
differ= .25 hr which is 15 min