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2 years ago

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In an all boys school, the heights of the student body are normally distributed with a mean of 69 inches and a standard deviatio

n of 2.5 inches. Using the empirical rule, what percentage of the boys are between 61.5 and 76.5 inches tall?

1 answer:

Molodets [167]2 years ago

7 0

Step-by-step explanation:

plus of yhis number and solve it oksy

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Suppose that 1/2 of all cars sold at a Nissan dealer in a given year are Altimas, 1/3 are Maximas, and the rest are Sentras. Sup

IRINA_888 [86]

Answer:

(1) Not conditional, 5/8

(2) Not conditional, 1/12

(3) Conditional, 1/18

Step-by-step explanation:

Fraction of cars sold

Altima = 1/2

Maxima = 1/3

Sentra = 1 - (1/2 + 1/3) = 1 - 5/6 = (6 - 5)/6 = 1/6

Fraction of cars sold with moon roof

Altima = 3/4 × 1/2 = 3/8

Maxima = 1/2 × 1/3 = 1/6

Sentra = 1/2 × 1/6 = 1/12

(1) Probability (a randomly selected car has a moon roof) = 3/8 + 1/6 + 1/12 = (9+4+2)/24 = 15/24 = 5/8

(2) Probability (a randomly selected car has a moon roof given it is Sentra) = 1/12

(3) Probability (a randomly selected car is a Maxima if it has a moon roof) = 1/3 × 1/6 = 1/18

A conditional probability uses if (as a condition) in making statements or asking questions

An unconditional probability makes statement or ask question without the use of condition (if)

5 0

2 years ago

The frequency table was made using a box containing slips of paper. Each slip of paper was numbered 0, 1, 2, 3, or 4.

inna [77]

In order to make a frequency plot first we need to find the proportion of each outcome.

Total number of results = 15+20+5+5+5 = 50

Frequency of 0 = 15
Proportion of 0 = 15/50 = 0.3

Frequency of 1 = 20
Proportion of 0 = 20/50 = 0.4

Frequency of 2 = 5
Proportion of 2 = 5/50 = 0.1

Frequency of 3 = 5
Proportion of 3 = 5/50 = 0.1

Frequency of 4 = 5
Proportion of 4 = 5/50 = 0.1

Now we need to plot the data on a frequency plot. The x-axis shows the outcomes from 0 to 4 and y-axis shows the frequency of each outcomes. The frequency plot is shown in the figure attached with.

4 0

3 years ago

Read 2 more answers

Identify a possible first step using the elimination method to solve the system and then find the solution to the system. 3x - 5

irina1246 [14]

ans is b...multiply eqn 1 by -2 and eqn 2 by 3

=》 -6x + 10y = 4...eqn 3

=》 6x + 3y = 9...eqn 4

add eqn 3 and 4...

=》13y = 13

=》y =1 and x = 1

5 0

2 years ago

The amount of money in Mark's bank account after x months is given by the function

Murrr4er [49]

Y=mx+b
Mx is the rate of change
B is your starting point
Started with 1000, A
-200 is the rate of change, D

4 0

2 years ago

The probability that your call to a service line is answered in less than 30 seconds is 0.75. Assume that your calls are indepen

vfiekz [6]

Answer:

a) 0.2581

b) 0.4148

c) 17

Step-by-step explanation:

For each call, there are only two possible outcomes. Either they are answered in less than 30 seconds. Or they are not. The probabilities for each call are independent. So we use the binomial probability distribution to solve this question.

Binomial probability distribution

The binomial probability is the probability of exactly x successes on n repeated trials, and X can only have two outcomes.

$P(X = x) = C_{n,x}.p^{x}.(1-p)^{n-x}$

In which $C_{n,x}$ is the number of different combinations of x objects from a set of n elements, given by the following formula.

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

And p is the probability of X happening.

In this problem we have that:

$p = 0.75$

a. If you call 12 times, what is the probability that exactly 9 of your calls are answered within 30 seconds? Round your answer to four decimal places (e.g. 98.7654).

This is $P(X = 9)$ when $n = 12$ . So

$P(X = x) = C_{n,x}.p^{x}.(1-p)^{n-x}$

$P(X = 9) = C_{12,9}.(0.75)^{9}.(0.25)^{3} = 0.2581$

b. If you call 20 times, what is the probability that at least 16 calls are answered in less than 30 seconds? Round your answer to four decimal places (e.g. 98.7654).

This is $P(X \geq 16)$ when $n = 20$

So

$P(X \geq 16) = P(X = 16) + P(X = 17) + P(X = 18) + P(X = 19) + P(X = 20)$

$P(X = x) = C_{n,x}.p^{x}.(1-p)^{n-x}$

$P(X = 16) = C_{20,16}.(0.75)^{16}.(0.25)^{4} = 0.1897$

$P(X = 17) = C_{20,17}.(0.75)^{17}.(0.25)^{3} = 0.1339$

$P(X = 18) = C_{20,18}.(0.75)^{18}.(0.25)^{2} = 0.0669$

$P(X = 19) = C_{20,19}.(0.75)^{19}.(0.25)^{1} = 0.0211$

$P(X = 20) = C_{20,20}.(0.75)^{20}.(0.25)^{0} = 0.0032$

So

$P(X \geq 16) = P(X = 16) + P(X = 17) + P(X = 18) + P(X = 19) + P(X = 20) = 0.1897 + 0.1339 + 0.0669 + 0.0211 + 0.0032 = 0.4148$

c. If you call 22 times, what is the mean number of calls that are answered in less than 30 seconds? Round your answer to the nearest integer.

The expected value of the binomial distribution is:

$E(X) = np$

In this question, we have $n = 22$

So

$E(X) = 22*0.75 = 16.5$

The closest integer to 16.5 is 17.

7 0

2 years ago