Answer:
a) 20.16; b) 20.49 and 21.51
Step-by-step explanation:
We use z scores for each of these. The formula for a z score is
.
For part a, we want the 20th percentile; this means we want 20% of the data to be lower than this. We find the value in the cells of the z table that are the closest to 0.20 as we can get; this is 0.2005, which corresponds with a z score of -0.84.
Using this, 21 as the mean and 1 as the standard deviation,
-0.84 = (X-21)/1
-0.84 = X-21
Add 21 to each side:
-0.84+21 = X-21+21
20.16 = X
For part b, we want the middle 39%. This means we want 39/2 = 19.5% above the mean and 19.5% below the mean; this means we want
50-19.5 = 30.5% = 0.305 and
50+19.5 = 69.5% = 0.695.
Looking these values up in the cells of the z table, we find those exact values; 0.305 corresponds with z = -0.51 and 0.695 corresponds with z = 0.51:
-0.51 = (X-21)/1
-0.51 = X-21
Add 21 to each side:
-0.51+21 = X-21+21
20.49 = X
0.51 = (X-21)/1
0.51 = X-21
Add 21 to each side:
0.51+21 = X-21+21
21.51 = X
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.
Answer:
The answer is B) -5
Step-by-step explanation:
It is -5 because if you take monday's temperature and subtract it by tuesday's temperature. You get -5
-2-3=-5
Answer: 
Step-by-step explanation:
1. A number written in scientific notation has the following form:
Where is 
is a number between 1 and 10 but not including 10, and b is an integer.
2. The negative exponent indicates the number of places the decimal point must be moved to the left to obtain the number as a decimal number.
3. Keeping this on mind, you can know that: if the exponent of a number written in scientific notation indicates that the decimal point must be moved 5 places to the left and another number written in scientific notation indicates that the decimal point must be moved 2 places to the left, then the first number is smaller than the second one.
4. Therefore, you can arrange the numbers given in the problem as following:
Answer:
QR=18
Step-by-step explanation:
QR/QO =QS/QP (proportionality theorem...OP||RS )
QR/39 =24/52
52QR = 24(39)
52Q2=936
QR=18
