andy gets 7 out of 25wrtong in his maths test what fraction of the questions does andy answer correctly
2 answers:
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Answer:
a)
b)
And adding these values we got:
c) We can find the expected value given by:
And the standard deviation would be:
We can use the approximation to the normal distribution and we have at leat 95% of the data within 2 deviations from the mean. And the lower limit for this case would be:
And then we can consider a value of 18 as unusual lower for this case.
Step-by-step explanation:
Let X the random variable of interest "number cleared by arrest or exceptional", on this case we can model this variable with this distribution:
The probability mass function for the Binomial distribution is given as:
Where (nCx) means combinatory and it's given by this formula:
Part a
We want this probability:
Part b
We want this probability:
We can find the individual probabilities:
And adding these values we got:
Part c
We can find the expected value given by:
And the standard deviation would be:
We can use the approximation to the normal distribution and we have at leat 95% of the data within 2 deviations from the mean. And the lower limit for this case would be:
And then we can consider a value of 18 as unusual lower for this case.
Step-by-step explanation:
making m the subject first by dividing through by 4
from the question, given n = -1 ,0 ,1
so when n= -1
when n=0
when n=1