A coordinate grid with 2 lines. The first line is labeled y equals 0.5 x plus 3.5 and passes through (negative 3, 1), (negative
2 answers:
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Answer:
a: 28 < µ < 34
Step-by-step explanation:
We need the mean, var, and standard deviation for the data set. See first attached photo for calculations for these...
We get a mean of 222/7 = 31.7143
and a sample standard deviation of: 4.3079
We can now construct our confidence interval. See the second attached photo for the construction steps.
They want a 90% confidence interval. Our sample size is 7, so since n < 30, we will use a t-score. Look up the value under the 10% area in 2 tails column, and degree of freedom is 6 (degree of freedom is always 1 less than sample size for confidence intervals when n < 30)
The t-value is: 1.943
We rounded down to the nearest person in the interval because we don't want to over estimate. It said 28.55, so more than 28 but not quite 29, so if we use 29 as the lower limit, we could over estimate. It's better to use 28 and underestimate a little when considering customer flow.
Answer:
0.0406, 0.8284,0.7887
Step-by-step explanation:
Given that Mattel Corporation produces a remote-controlled car that requires three AA batteries
X is N(34, 5.5)
Hence sample size of 25 would follow a t distribution with df = 24
This is because sample size <30
t distribution with df 24 would be bell shaped symmetrical about the mean and unimodal.
Std error of sample mean = std dev /sqrt n=
Prob (X>36) =
i.e nearly 4.1% of the sample would have a mean useful life of more than 36 hours
X>33.5 implies
=0.82837
=0.8284 proportion will have a mean useful life greater than 33.5 hours
Proportion between 33.5 and 36 hours
=