patty is building a rope ladder for a tree house. she needs two 5-foot pieces of rope for th esides fo the ladder. she needs 7 p
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Answer:
Normal Distribution
Standard error = 0.473
Step-by-step explanation:
We are given the following information:
A procurement specialist has purchased 25 resistors from vendor 1 are assumed to be normally distributed with mean 100 ohms and standard deviation 1.5 ohms.
A procurement specialist has purchased 30 resistors from vendor 2 are assumed to be normally distributed with mean 105 ohms and standard deviation 2.0 ohms.
The difference of two independent normally distributed random variables is normal, with its mean being equal to the difference of the two means, and its variance being the sum of the two variances.
Thus, the sampling distribution of is a normal distribution.
Mean =
Standard error =
Answer:
a) 0.625; b) 16.879; c) 8.442
Step-by-step explanation:
Since this is a normal distribution, we want the value of the mean, μ: 2.2; and the value of the standard deviation, σ: 6.3.
For the 40th percentile, we look in a z chart. We want to find the value as close to 0.40 as we can get; this is 0.4013, and it corresponds to a z score of z = -0.25.
Our formula for a z score is . Using our values, we have
-0.25 = (X-2.2)/6.3
Multiply both sides by 6.3:
6.3(-0.25) = X-2.2
-1.575 = X-2.2
Add 2.2 to each side:
-1.575+2.2 = X-2.2+2.2
0.625 = X
For the 99th percentile, the value in the z chart closest to 0.99 is 0.9901, which corresponds to a z score of z = 2.33:
2.33 = (X-2.2)/6.3
Multiply both sides by 6.3:
6.3(2.33) = X-2.2
14.679 = X-2.2
Add 2.2 to each side:
14.679+2.2 = X-2.2+2.2
16.879 = X
For the IQR, we find the values for the 75th percentile (Q3) and the 25th percentile (Q1). The value in a z chart closest to 0.75 is 0.7486, which corresponds to a z score of z = 0.67:
0.67 = (X-2.2)/6.3
Multiply both sides by 6.3:
6.3(0.67) = X-2.2
4.221 = X-2.2
Add 2.2 to each side:
4.221+2.2 = X-2.2+2.2
6.421 = X
The value in a z chart closest to 0.25 is 0.2514, which corresponds to a z score of z = -0.67:
-0.67 = (X-2.2)/6.3
Multiply both sides by 6.3:
6.3(-0.67) = X-2.2
-4.221 = X-2.2
Add 2.2 to each side:
-4.221+2.2 = X-2.2+2.2
-2.021 = X
This makes the interquartile range
6.421--2.021 = 8.442