Someone help me with this math problem please??

Question

bill left his house at 1:20 pm and traveled at 30 mph. his sister left later and traveled over the same road at 45 mph. both arrived at their destination at 4:20 pm. at what time did bill's sister leave the house?

this problem is killing me

Answer 1

Make it two problems.

Bill left at 1:20, arrived at 4:20, that's 3 hours.

3 hours at 30 mph, how far did he go?

It's easy math, I'll give you that one, 90 miles.

NOW the sister went the same distance, 90 miles, right?

She was going 45 mph, so divide to get how many hours it took her.

She arrived at 4:20, same as Bill.  So subtract out, and get when she left.

Answer 2

ok bill left at 1:20 pm and travelled 3 hours at 30mph, which means he travelled 90 miles.

his sister travelled at 45 mph, and so her trip would of taken 2 hours

there fore you take 2 hours off 4.20 pm to find out what time she left.

so she left at 2.20 pm

Answer 3

First, analyze the problem carefully...Bill left at 1:20pm and arrived at 4:20pm...therefore he traveled for 3 hours (4:20pm-1:20pm = 3hrs)

then you can compute for the length of the road he traveled because his speed was given:

speed = distance/time

distance = speed x time

distance = (30miles/hr) x 3hrs

distance = 90miles

we can use the same formula to compute the time his sister traveled since we have the distance and the speed of his sister...

speed = distance/time

time = distance/speed = 90 miles/ (45miles/hr)

time = 2 hrs

since she traveled for 2hrs, and arrived at 4:20pm, then...

time she left the house = 4:20pm - 2hrs = 2:20pm

therefore, she left the house at 2:20pm (i.e. 1hour after bill left, because bill traveled for 3hrs, while she traveled for only 2hrs, and both arrived at 4:20pm)

Answer 4

Bill travelled for 3 hours at a rate of 30 mph, so he travelled a total of 90 miles.

Bill's sister travelled 90 miles at a rate of 45 mph, so she must have been travelling for 2 hours.

If Bill's sister arrived at 4:20pm, she must have left at 2:20pm.