John went on a bike ride to the store 4 miles away. If it took John 3/10 of an hour to get there and 1/2 of an hour to get back, what was his average rate of speed (miles per hour) for the entire trip?

The round trip was 8 miles ( 4 + 4 = 8)

The total time for the trip is 3/10 + 1/2

Rewrite 1/2 as 5/10

Now add 3/10 + 5/10 = 8/10 = 4/5 hour for the 8 mile trip.

Now to find miles per hour, divide total miles by total time:

8 miles / 4/5 hour

When you divide by a fraction flip the fraction over and multiply:

8 x 5/4 = 40/4 = 10

The average rate was 10 miles per hour.

a

step-by-step explanation:

85.560%

step-by-step explanation:

conditional probability is defined as:

p(a|b) = p(a∩b) / p(b)

in other words, the probability that a occurs, given that b has occurred = the probability that both a and b occur / the probability that b occurs.

in this example:

p(turns 64 | turns 44) = p(turns 64 & turns 44) / p(turns 44).

if someone turns 64, they must have already turned 44, so:

p(turns 64 | turns 44) = p(turns 64) / p(turns 44)

on page 42, we see that of the original 100,000, 94944 turn 44, and 81234 turn 64.   therefore:

p(turns 64 | turns 44) = 81234 / 94944

p(turns 64 | turns 44) = 0.85560