There are 75 students in a speech contest. Yesterday 1/5 of them gave their speech. Today, 3/5 of the remaining students gave th
1 answer:
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Answer:
a)
And we want the probability from 0 to two deviations above the mean and we got 95/2 = 47.5 %
b)
So one deviation below the mean we have: (100-68)/2 = 16%
c)
For this case below 2 deviation from the mean we have 2.5% and above 1 deviation from the mean we got 16% and then the percentage between -2 and 1 deviation above the mean we got: (100-16-2.5)% = 81.5%
Step-by-step explanation:
For this case we have a random variable with the following parameters:
From the empirical rule we know that within one deviation from the mean we have 68% of the values, within two deviations we have 95% and within 3 deviations we have 99.7% of the data.
We want to find the following probability:
We can find the number of deviation from the mean with the z score formula:
And replacing we got
And we want the probability from 0 to two deviations above the mean and we got 95/2 = 47.5 %
For the second case:
So one deviation below the mean we have: (100-68)/2 = 16%
For the third case:
And replacing we got:
For this case below 2 deviation from the mean we have 2.5% and above 1 deviation from the mean we got 16% and then the percentage between -2 and 1 deviation above the mean we got: (100-16-2.5)% = 81.5%
First, let's simplify the inequality as much as we can:
-4x + 7 > 15
-4x > 8
Divide by -4:
x < -2
-4x + 7 > 15
-4x > 8
Divide by -4:
x < -2