De'Jhan went to the movies during our snow days and watched all 8 Spider-Man movies. Each movie cost $11. How much did De'Jhan s
2 answers:
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Answer:
(a) Customer will not purchase the light bulbs at significance level of 0.05
(b) Customer will purchase the light bulbs at significance level of 0.01 .
Step-by-step explanation:
We are given that Light bulbs of a certain type are advertised as having an average lifetime of 750 hours. A random sample of 50 bulbs was selected, and the following information obtained:
Average lifetime = 738.44 hours and a standard deviation of lifetimes = 38.2 hours.
Let Null hypothesis, :
= 750 {means that the true average lifetime is same as what is advertised}
Alternate Hypothesis, :
< 750 {means that the true average lifetime is smaller than what is advertised}
Now, the test statistics is given by;
T.S. = ~
where, X bar = sample mean = 738.44 hours
s = sample standard deviation = 38.2 hours
n = sample size = 50
So, test statistics = ~
= -2.14
(a) Now, at 5% significance level, t table gives critical value of -1.6768 at 49 degree of freedom. Since our test statistics is less than the critical value of t, so which means our test statistics will lie in the rejection region and we have sufficient evidence to reject null hypothesis.
Therefore, we conclude that the true average lifetime is smaller than what is advertised and so consumer will not purchase the light bulbs.
(b) Now, at 1% significance level, t table gives critical value of -2.405 at 49 degree of freedom. Since our test statistics is higher than the critical value of t, so which means our test statistics will not lie in the rejection region and we have insufficient evidence to reject null hypothesis.
Therefore, we conclude that the true average lifetime is same as what it has been advertised and so consumer will purchase the light bulbs.
Answer:
The probability that the maximum speed is at most 49 km/h is 0.8340.
Step-by-step explanation:
Let the random variable<em> </em><em>X</em> be defined as the maximum speed of a moped.
The random variable <em>X</em> is Normally distributed with mean, <em>μ</em> = 46.8 km/h and standard deviation, <em>σ</em> = 1.75 km/h.
To compute the probability of a Normally distributed random variable we first need to convert the raw score of the random variable to a standardized or <em>z</em>-score.
The formula to convert <em>X</em> into <em>z</em>-score is:
Compute the probability that the maximum speed is at most 49 km/h as follows:
Apply continuity correction:
P (X ≤ 49) = P (X < 49 - 0.50)
= P (X < 48.50)
*Use a <em>z</em>-table for the probability.
Thus, the probability that the maximum speed is at most 49 km/h is 0.8340.