power prep

[dunkin77]

If the speed of X meters per second is equivalent to the speed of y kilometers per hour, what is y in terms of x?

a) 5x/18
b) 6x/5
c) 18x/5
d) 60x
e) 3,600,000x


Hi,
for some reason my answer was 18/5x but The correct answer is C) -- can anyone explain ?

[parore26]

The speed is X m/sec. Therefore, the speed in terms of metres/hr is 3600X metres/hour.

The speed in terms of KM /hour is (3600/1000) X KM/H .

Y = (18/5)X

Hope this helps.

[Cybermusings]

x m/sec = y km/hr
y*1000 / 60*60 = x m /sec
1000y / 3600 = x
y = 3600x/1000 = 36x/10 = 18x/5
BTW...thats the same as your answer isn't it....the only diff is that x is in the numerator and not the denominator...

[Scott@TargetTestPrep]

If the speed of X meters per second is equivalent to the speed of y kilometers per hour, what is y in terms of x?

a) 5x/18
b) 6x/5
c) 18x/5
d) 60x
e) 3,600,000x

There are 3,600 seconds in an hour and 1,000 meters in a kilometer. So, let's convert y kilometers/hour to meters/second:

We can start by converting y kilometers to meters.

y kilometers = 1,000y meters

Next, we can convert 1 hour to seconds.

1 hour = 3,600 seconds

Thus, y km/hr can be expressed as 1,000y/3,600 m/sec, or 5y/18 m/sec, after it's simplified.

Since our two rates are equal, x = 5y/18. We need to solve this equation for y.

18x = 5y

18x/5 = y

Answer: C