Homework Help: Math

Posted by Elizabeth on Monday, December 10, 2012 at 10:16am.

A motorist makes a journey of 240 km from Singapore to Malacca to visit his inlaws at an average speed of x kilometers.

On his return journey, his average speed is reduced by 6km/hour due to traffic.

If the return journey takes 20 minutes longer, form an equation with x and solve it to find the average speed of each journey, giving your answer correct to two decimal places.

So: 240/x is the number of hours taken for the first journey.

240/x-6 is the time it takes for the return journey.

What do I do next? Please help!

Math - Steve, Monday, December 10, 2012 at 10:31am
and you know that the return journey takes 1/3 hour longer than the one going.

240/x + 1/3 = 240/(x-6)
x = 3(1+ą481) = 68.80

check:
240/62.80 = 3.82
240/68.80 = 3.49 = 3.82
difference: .33 hr = 20 min

you got the setup right, but didn't take that final step. Be sure to analyze everything they tell you, and the solution will emerge.
Math - Steve, Monday, December 10, 2012 at 10:32am
oops. typo that's
3(1ą√481)
Math - Elizabeth, Monday, December 10, 2012 at 10:48am
thanks!

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