Answer:
72
Step-by-step explanation:
you take 85 * 9
85 = # of seats
9 = # of buses
then you get 765
next, you take 765 - 693
765 = # of seats
693 = # people who bought tickets for a trip
finally you get 72
72 = # of empty seats
Answer:
b. the area to the right of 2
Step-by-step explanation:
Problems of normally distributed samples are solved using the z-score formula.
In a set with mean 
and standard deviation 
, the zscore of a measure X is given by:
The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X, which is also the area to the left of Z. Subtracting 1 by the pvalue, we get the probability that the value of the measure is greater than X, which is the area to the right of Z.
In this problem:
Percentage who did better:
P(Z > 2), which is the area to the right of 2.
Answer:
$110
Step-by-step explanation:
Let a, b, and c represent the earnings of Alan, Bob, and Charles. The problem statement tells us ...
a + b + c = 480 . . . . . . the combined total of their earnings
-a + b = 40 . . . . . . . . . . Bob earned 40 more than Alan
2a - c = 0 . . . . . . . . . . . Charles earned twice as much as Alan
Adding the first and third equations, we get ...
(a + b + c) + (2a - c) = (480) + (0)
3a + b = 480
Subtracting the second equation gives ...
(3a +b) - (-a +b) = (480) -(40)
4a = 440 . . . . . . . . simplify
a = 110 . . . . . . . . . . divide by the coefficient of a
Alan earned $110.
_____
<em>Check</em>
Bob earned $40 more, so $150. Charles earned twice as much, so $220.
The total is then $110 +150 +220 = $480 . . . . as required
