Answer:
is that the question because I'm not sure
Answer:
The probability that a call last between 4.2 and 4.9 minutes is 0.4599
Step-by-step explanation:
Let X be the length in minutes of a random phone call. X is a normal distribution with mean λ=4.2 and standard deviation σ=0.4. We want to know P(4.2 < X < 4.9). In order to make computations, we will use W, the standarization of X, given by the following formula

We will use
, the cummulative distribution function of W. The values of
are well known and the can be found in the attached file

We conclude that the probability that a call last between 4.2 and 4.9 minutes is 0.4599
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Okay so you want to find out how many days would be needed to get 32 million new accounts.
First take 32÷0.4=80
Then your going to take 0.4×80=32
Answer:
£365
Step-by-step explanation:
so add another column and call it midpoint. use the weekly earnings column to find the midpoints add both numbers then divide by 2
then times all these numbers by the corresponding frequencies
1 * 200=200
11 * 300=3300
5 * 400=2000
0 * 500=0
3 * 600=1800
then add these numbers =7300 then do 7300/20=365