If a person blinks their eyes once every 3 minutes on the average, then how many times
1 answer:
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Answer:
a) 108 people with a standard deviation of 3.286335
b) No
c) 0.218163 or around 21.82%
d) See explanation below.
Step-by-step explanation:
This situation can be modeled with the Binomial Distribution which gives t<em>he probability of an event that occurs exactly k times out of n, and is given by </em>
<em>
</em>
<em>where </em>
<em>= combination of n elements taken k at a time.
</em>
<em>p = probability that the event (“success”) occurs once </em>
<em>q = 1-p </em>
In this case, the event “success” is finding an American adult who had chickenpox before adulthood with probability p=0.9
and n=120 American adults in the sample.
The <em>standard deviation for this binomial distribution</em> is
where <em>n is the sample size 120 </em>
a)
We consider a random sample of 120 American adults. How many people in this sample would you expect to have had chickenpox in their childhood?
If about 90% of American adults had chickenpox before adulthood, we expect to find 90% of 120 = 0.9*120=108 people in the sample who had chickenpox in their childhood.
The standard deviation would be
b)
Would you be surprised if there were 105 people who have had chickenpox in their childhood?
No, because 105 and 108 are in the interval [mean - s, mean +s]
c)
What is the probability that 105 or fewer people in this sample have had chickenpox in their childhood?
The probability that 105 or fewer people in this sample have had chickenpox in their childhood is
We compute this value easily with a spreadsheet and we get
d)
How does this probability relate to your answer to part (b)?
A binomial distribution with np>5 and nq>5 with n the sample size as is the case here, behaves pretty much like a Normal distribution with mean np and standard deviation , so around 60% of the data are in the interval [mean -s, mean +s] and 40% outside, so roughly <em>20% of the data should be in [0, mean-s] </em>
Answer:
$2.79 per pound of apples.
0.36 pounds per dollar.
The unit rate representing cost of per pound apples is typically used.
Step-by-step explanation:
We have been given that the weekly ad for a local grocery store advertises a 5 pound bag of organic apples for $13.95.
Since we know when rates are expressed as a quantity of 1, such as 100 meter per second or 5 miles per hour, they are called unit rates. We need to have 1 in our denominator to express two quantities as unit rate.
Let us find the unit rate in terms of cost of per pound bag of apples.
Therefore, our unit rate will be $2.79 per pound of apples.
Let us find unit rate of pounds of apples per dollar.
Therefore, our another unit rate will be 0.36 pounds per dollar.
Since, we purchase apples or other items according to their price per piece or their price per pound in our daily life, therefore, the unit rate representing cost of per pound apples is typically used.