Mathematics, 13.02.2020 23:27 leahjade0307

According to a survey conducted by Deloitte in 2017, 0.4775 of U. S. smartphone owners have made an effort to limit their phone use in the past. In a sample of 72 randomly selected U. S. smartphone owners, what is the probability that no more than 30 will have attempted to limit their cell phone use in the past?

1) 0.1801
2) 0.0278
3) 0.05554) 0.1246
5) 0.8199

Answers: 3

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Answers

Answer from: javi89

$P(X \leq 30)= P(X=0 + P(X=1) +....+ P(X=30)$

And it's easier to compute this in excel with the following formula:

"=BINOM.DIST(30,72,0.4775,TRUE)"

And we got:

$P(X \leq 30)= 0.1801$

So the correct option would be:

1) 0.1801

Step-by-step explanation:

Previous concepts

The binomial distribution is a "DISCRETE probability distribution that summarizes the probability that a value will take one of two independent values under a given set of parameters. The assumptions for the binomial distribution are that there is only one outcome for each trial, each trial has the same probability of success, and each trial is mutually exclusive, or independent of each other".

Let X the random variable of interest, on this case we now that:

$X \sim Binom(n=72, p=0.4775)$

The probability mass function for the Binomial distribution is given as:

$P(X)=(nCx)(p)^x (1-p)^{n-x}$

Where (nCx) means combinatory and it's given by this formula:

$nCx=\frac{n!}{(n-x)! x!}$

Solution to the problem

For this case we want to find the probability that no more than 30 will have attempted to limit their cell phone, so we want to find this:

$P(X \leq 30)$

Becuase no more than 30 means that the maximum value can be 30.

And we can find this probability like this:

$P(X \leq 30)= P(X=0 + P(X=1) +....+ P(X=30)$

And it's easier to compute this in excel with the following formula:

"=BINOM.DIST(30,72,0.4775,TRUE)"

And we got:

$P(X \leq 30)= 0.1801$

So the correct option would be:

1) 0.1801

Answer from: Quest

solution:

as, mean is defined as sum of all the observations divided by total number of observations.

and , median is mid value of the data whether arranged in ascending order or descending order.

consider, roadsters:

2,3,4,5,6,7,8,9

mean = $\frac{2+3+4+5+6+7+8+9}{8}=\frac{44}{8}=5.5$

also, median= $\frac{5+6}{2}=\frac{11}{2}=5.5$ , because number of observations is even, so median is mean of two mid values.

now, coming to bandits

2,3,4,5,6

mean = $\frac{2+3+4+5+6}{5}=\frac{20}{5}=4$

median = 4, as number of observations is odd.

so, roadsters has greater median as well mean than bandits.

→option a is true about the repairs performed on 2 types of cars:

bandits have lower median and mean than roadsters.

Answer from: Quest

do you mean add both of the equations together

because if you do the answer is 10x-5

step-by-step explanation:

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