I got 121 but im not sure if im right
1 answer:
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Answer:
95.15%
Step-by-step explanation:
We have that the mean (m) is equal to 20, the standard deviation (sd) 3
They ask us for P (x <25)
For this, the first thing is to calculate z, which is given by the following equation:
z = (x - m) / sd
We have all these values, replacing we have:
z = (25 - 20) / (3)
z = 1.66
With the normal distribution table (attached), we have that at that value, the probability is:
P (z <1.66) = 0.9515
Which means that the probability that it arrives before 25 minutes is 95.15%
So, this problem is asking us to find the value of our variable u.
How can you do this? By isolating the variable, or having only it on one side of the equals sign.
Here's the step by step approach. It's just simple algebra and reverse order of operation (which is what you should do whenever you are solving for a variable).
Multiply both sides by 11 to get rid of the 11 denominator.
Then, subtract both sides by 88 to get u by itself.
Therefore, u is equal to 99.
How can you do this? By isolating the variable, or having only it on one side of the equals sign.
Here's the step by step approach. It's just simple algebra and reverse order of operation (which is what you should do whenever you are solving for a variable).
Multiply both sides by 11 to get rid of the 11 denominator.
Then, subtract both sides by 88 to get u by itself.
Therefore, u is equal to 99.