The first one is B and the second is D
1) Mean Absolute Deviation = 1.75
2) Mean = 244
Step-by-step explanation:
In statistics, the empirical rule states that for a normally distributed random variable,
- 68.27% of the data lies within one standard deviation of the mean.
- 95.45% of the data lies within two standard deviations of the mean.
- 99.73% of the data lies within three standard deviations of the mean.
In mathematical notation, as shown in the figure below (for a standard normal distribution), the empirical rule is described as

where the symbol
(the uppercase greek alphabet phi) is the cumulative density function of the normal distribution,
is the mean and
is the standard deviation of the normal distribution defined as
.
According to the empirical rule stated above, the interval that contains the prices of 99.7% of college textbooks for a normal distribution
,

Therefore, the price of 99.7% of college textbooks falls inclusively between $77 and $149.
Answer: 9
Step-by-step explanation:
When you multiply 9*9, you get 81 whose sum is 9 (8+1)
Likewise, 9*8=72( 7+2=9)
52 - 38 is 14
since on the second they sold one more child ticket then the first day we know the extra money is the price of a child ticket
so 14 is how much a child ticket is
if 3 senior citizen tickets but 14$ = 38
subtract 14 from38 = 24
and then 24/3 =senior ticket
child:14$
senior:8$