Answer:
68% of jazz CDs play between 45 and 59 minutes.
Step-by-step explanation:
<u>The correct question is:</u> The playing time X of jazz CDs has the normal distribution with mean 52 and standard deviation 7; N(52, 7).
According to the 68-95-99.7 rule, what percentage of jazz CDs play between 45 and 59 minutes?
Let X = <u>playing time of jazz CDs</u>
SO, X ~ Normal()
The z-score probability distribution for the normal distribution is given by;
Z = ~ N(0,1)
Now, according to the 68-95-99.7 rule, it is stated that;
- 68% of the data values lie within one standard deviation points from the mean.
- 95% of the data values lie within two standard deviation points from the mean.
- 99.7% of the data values lie within three standard deviation points from the mean.
Here, we have to find the percentage of jazz CDs play between 45 and 59 minutes;
For 45 minutes, z-score is = = -1
For 59 minutes, z-score is = = 1
This means that our data values lie within 1 standard deviation points, so it is stated that 68% of jazz CDs play between 45 and 59 minutes.
Tammy's sample may not be considered valid because, on the first hand, it is said that she only asked students from her " Math Class".
If she wants to have a survey to find out the favorite subject of the students at her school, she must conduct a survey involving all the students in her school, not just in her class. What she did is just subjective. She should use a tally listing the different subjects and compare the number of students per subject. This way, she can have an objective representation of the least liked subjects and the most liked subjects of the students on her school.
Illustrating her survey through statistics may be more reliable and valid because it shows frequencies in which she can calculate easily and accurately the percentage of the number of students per subject, in a more objective manner.
Answer:
94 cents?
Step-by-step explanation:
2%*40=80%
1.80*0.52=0.936
In 40 years, mail may cost about 94 cents.
(I think this is the correct answer ://)
If an hour has 60 minutes and a day has 24 hours , there are 60 times 24 in a day
60*24 = 1440
There are 1440 minutes in a day !
I hope that's help !