The empirical probability of a 4 or 5 is
(count of outcome = 4 or 5)/(count of all outcomes) = (44 +40)/240 = 7/20
The problem statement asks you to assume the outcomes will remain in this proportion going forward. That is, the number of outcomes (n) of 4 or 5 in the next 60 rolls of the number cube is expected to satisfy
7/20 = n/60
Multiplying that by 60 gives
n = 60*(7/20) = 21
Selection D is appropriate.
Her rate of reading was = 51/2 /12 = 51/24 per hour
It means she red 51/24 pages in one hour
Remark
The easy way to do this is to change 5/8 to a decimal and worr y about changing it back to a fraction if you need to.
15 5/8 = 15.625 The easy way to find 5/8 is to use your calculator. 5 ÷ 8 = on most calculators.
You want 12 of these
1 leg is 15.625 inches long.
12 legs = x
1/12 = 15.625 / x Cross multiply
x = 12 * 15.625
x = 187.5 inches
Just how many feet is that? Divide by 12 to get the number of feet 187.5 / 12 =
15.625 feet.
Usually 2 by 4s are 8 or 12 feet long. For 8 feet you will need 2 of them and for 12 feet unfortunately you will need two as well.
