SDT

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SDT

by uptowngirl92 » Sun Sep 20, 2009 2:26 am
If Bill drove 1.5 times slower than normal and was late for school today, how long does it normally take Bill to drive to school? (Assume that each day Bill takes the same route).

It took Bill 15 minutes longer to drive to school today than normal.
The distance between home and school is 15 miles.

trouble forming equations:(

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30 min

by aa2kash » Sun Sep 20, 2009 7:42 am
Let x be the normal speed. and t is the normal time
then equation 1 can be
xt=15

if he is 1.5times slower than normal speed.then new speed is 2x/3. and as he takes 15 min extra 1.e 1/4 hrs

equation 2 will be
2x/3=15/(t+1/4)
solving these 2 u get
x=30 and t=1/2 i.e 30 mins