In a "torture test" a light switch is turned on and off until it fails. if the probability that the switch will fail any time it
1 answer:
The probability that the switch does not fail is 1-0.001=0.999. In order to switch the lights off and on 1200 times, we need to press the switch 2400 times. Each event is assumed independent from the others; when we press the switch, its probability that it will fail is not influenced by the previous pressing of the switch. Thus, the probability that it won't fail after 2 times is 0.999*0.999=0.999^2. Similarly, we get that the required probability is : 
This is a relatively low probability. We see that even if the probability that the switch fails one time is very low, after many repetitions it becomes quite probable that the switch will fail at least one time.
This is a relatively low probability. We see that even if the probability that the switch fails one time is very low, after many repetitions it becomes quite probable that the switch will fail at least one time.
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Answer:
We failed to reject H₀
Z > -1.645
-1.84 > -1.645
We failed to reject H₀
p > α
0.03 > 0.01
We do not have significant evidence at a 1% significance level to claim that less than 40% of U.S. cell phone owners use their phones for most of their online browsing.
Step-by-step explanation:
Set up hypotheses:
Null hypotheses = H₀: p = 0.40
Alternate hypotheses = H₁: p < 0.40
Determine the level of significance and Z-score:
Given level of significance = 1% = 0.01
Since it is a lower tailed test,
Z-score = -2.33 (lower tailed)
Determine type of test:
Since the alternate hypothesis states that less than 40% of U.S. cell phone owners use their phone for most of their online browsing, therefore we will use a lower tailed test.
Select the test statistic:
Since the sample size is quite large (n > 30) therefore, we will use Z-distribution.
Set up decision rule:
Since it is a lower tailed test, using a Z statistic at a significance level of 1%
We Reject H₀ if Z < -1.645
We Reject H₀ if p ≤ α
Compute the test statistic:
From the z-table, the p-value corresponding to the test statistic -1.84 is
p = 0.03288
Conclusion:
We failed to reject H₀
Z > -1.645
-1.84 > -1.645
We failed to reject H₀
p > α
0.03 > 0.01
We do not have significant evidence at a 1% significance level to claim that less than 40% of U.S. cell phone owners use their phones for most of their online browsing.
The measure of angle ABC is 45°
<em><u>Explanation</u></em>
Vertices of the triangle are: A(7, 5), B(4, 2), and C(9, 2)
According to the diagram below....
Length of the side BC (a)
Length of the side AC (b)
Length of the side AB (c)
We need to find ∠ABC or ∠B . So using <u>Cosine rule</u>, we will get...
So, the measure of angle ABC is 45°
