Answer:
a) P(2)=0.270
b) P(X>3)=0.605
c) P=0.410
Step-by-step explanation:
We know that customers arrive at a grocery store at an average of 2.1 per minute. We use the Poisson distribution:
a) In this case: 
Therefore, the probability is P(2)=0.270.
b) In this case: 
Therefore, the probability is P(X>3)=0.605.
c) We know that two customers came in in the first minute. That is why we calculate the probability of at least 5 customers entering the other 2 minutes.
In this case:
Therefore, the probability is P=0.410.
When you roll two numbers you have four kinds of outcomes: EE, EO, OE, OO (where E = even, O = odd).
You get an even sum only if you sum two numbers that are both even or both odd, therefore the outcomes wanted are two: EE and OO.
Therefore:
P(sum is even) = 2 / 4 = 0.5
Hence, there is a 50% probability that, when you roll two numbers, their sum will be even.
This is a bit confusing, double check if you typed everything correctly.
Answer:
For this distribution of test scores, the standard deviation is equal to the square root of 9
D) 9
Step-by-step explanation:
We need to know the standard deviation formula:
(1)
Where:
S: Standard deviation
sum: Summation
x: Sample values
Am: Arithmetic mean
n:
Number of terms, in this case 3
Now, we need to know the arithmetic mean of the sample values: 2, 5 and 8
To know the standard deviation we need to have the summation of each term minus the arithmetic mean squared.
of each term:
Now, we can find the standard deviation:
The standard deviation is equal to the square root of 9
