+545 Norma and David crawled to the barn and then hopped back to the house. They crawled at 300 centimeters per minute and hopped at 400 centimeters per minute. If the round trip took 7 minutes, how many minutes did they crawl?
HELP I HAVE NO IDEA WHAT I'M DOING!!!
+33661 Let the distance from house to barn be L. Distance = speed*time, so
L = 300*t1 (1) where t1 is time to get from house to barn
L = 400*t2 (2) where t2 is time to get from barn to house
t1 + t2 = 7 (3)
From (1) and (2) we have 300*t1 = 400*t2 so, dividing both sides by 400 we have t2 = 3*t1/4. Put this into (3) to get:
t1 + 3*t1/4 = 7 or 7*t1/4 = 7 or t1 = 4
t1 is the time they crawled, so crawling time = 4 minutes.
+129852 Let m be the minutes they crawled....then 7 - m = the minutes they hopped
And R *T = D .... and D is the same in both cases....therefore.....
300 * m = 400 * (7 - m) simplify
300m = 2800 - 400m add 400 m to both sides
700m = 2800 divide both sides by 700
m = 4 minutes = time they crawled
