Answer:
The sample proportion represents a statistically significant difference from 50%
Step-by-step explanation:
Null hypothesis: The sample proportion is the same as 50%
Alternate hypothesis: The sample proportion is not the same as 50%
z = (p' - p) ÷ sqrt[p(1 - p) ÷ n]
p' is sample proportion = 289/400 = 0.7225
p is population proportion = 50% = 0.5
n is number of students sampled = 400
z = (0.7225 - 0.5) ÷ sqrt[0.5(1 - 0.5) ÷ 400] = 0.2225 ÷ 0.025 = 8.9
The test is a two-tailed test. Using a 0.01 significance level, critical value is 2.576. The region of no rejection of the null hypothesis is -2.576 and 2.576.
Conclusion:
Reject the null hypothesis because the test statistic 8.9 falls outside the region bounded by the critical values -2.576 and 2.576.
There is sufficient evidence to conclude that the sample proportion represents a statistically significant difference from 50%.
Answer:
The parameters of the exponential distribution is 0.0133.
Step-by-step explanation:
Exponential distribution is a continuous probability distribution.
The density function of exponential distribution is,

Here the parameter θ is the reciprocal of the mean of the random variable <em>X</em>.
The random variable <em>X</em> has an average value of 75 seconds.
Compute the parameters of the exponential distribution as follows:


Thus, the parameters of the exponential distribution is 0.0133.
Answer:

Step-by-step explanation:

Answer:

Step-by-step explanation:
Starting from the top, the ant can only take four different directions, all of them going down, every direction has a probability of 1/4. For the second step, regardless of what direction the ant walked, it has 4 directions: going back (or up), to the sides (left or right) and down. If the probability of the first step is 1/4 for each direction and once the ant has moved one step, there are 4 directions with the same probability (1/4 again), the probability of taking a specific path is the multiplication of the probability of these two steps:

There are only 4 roads that can take the ant to the bottom in 2 steps, each road with a probability of 1/16, adding the probability of these 4 roads:

The probability of the ant ending up at the bottom is
or 0.25.
Answer:
0.9999
Step-by-step explanation:
Let X be the random variable that measures the time that a switch will survive.
If X has an exponential distribution with an average life β=44, then the probability that a switch will survive less than n years is given by
So, the probability that a switch fails in the first year is
Now we have 100 of these switches installed in different systems, and let Y be the random variable that measures the the probability that exactly k switches will fail in the first year.
Y can be modeled with a binomial distribution where the probability of “success” (failure of a switch) equals 0.0225 and
where
equals combinations of 100 taken k at a time.
The probability that at most 15 fail during the first year is