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Vera_Pavlovna [14]
2 years ago
11

A calculus student takes a 20-question, multiple choice test with 5 answer choices for each question. find the probability of ge

tting at least 70% of the questions correct?
Mathematics
2 answers:
ehidna [41]2 years ago
8 0

Answer:

1.66479*10^(-6)

Step-by-step explanation:

to get 70% correct question out of 20 the student have correct 14 questions correct.

probability of getting answer correct p= 1/5=0.2

probability of getting answer wrong q= 4/5=0.8

its case of binomial distribution where

n= 20, r= 14 , p= 0.2 and q= 0.8

therefore

[tex]_{20}^{14}\textrm{C}\times 0.2^{14}\times0.8^{6}[\tex]

solving we get

1.66479*10^(-6)

lisabon 2012 [21]2 years ago
7 0
The probability would be 0.000017.

70% of the 20 questions is 14 questions correct.  Using a binomial distribution for this, we have:

_{20}C_{14}(0.2)^{14}\times (1-0.2)^{20-14}
\\
\\ \frac{20!}{14!6!}\times (0.2)^{14} \times (0.8)^6
\\
\\ \approx 0.000017
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Step-by-step explanation:

71+25=96

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A department store sells logo shirts at an original price of $20. Every month that a shirt doesn’t sell, the store reduces the s
Tasya [4]
Given:
Original price = 20
reduces selling price by 25% every month it's not sold.

First markdown month:
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Second markdown month
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The pre-tax price of the shirt for Macy will be $5.63
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2 years ago
Read 2 more answers
In the last two weeks of a sale, prices are reduced first by 30% and then by a further 40% of the new price . What is the final
Mandarinka [93]
15 x .30 = 4.50 discount     15-4.50= 10.50
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5 0
2 years ago
On average, the number of customers who had items to return for refunds or exchanges at a certain retail store's service desk is
spayn [35]

Answer:

The probability that the service desk will have at least 100 customers with returns or exchanges on a randomly selected day is P=0.78.

Step-by-step explanation:

With the weekly average we can estimate the daily average for customers, assuming 7 days a week:

M=756/7=108

We can model this situation with a Poisson distribution, with parameter λ=108. But because the number of events is large, we use the normal aproximation:

P(\lambda)\approx N(\lambda,\lambda)

Then we can calculate the z value for x=100:

z=\frac{x-\mu}{\sigma}=\frac{100-108}{\sqrt{108}}=\frac{-8}{10.4} =-0.77

Now we calculate the probability of x>100 as:

P(x>100)=P(z>-0.77)=0.78

The probability that the service desk will have at least 100 customers with returns or exchanges on a randomly selected day is P=0.78.

5 0
2 years ago
Chadwick bought 50 shares of Chipotle stock on Nov 1, 2016 for $396.33 share. He sold the shares four years later, with the per
scoray [572]

Answer:

Step-by-step explanation:

Given the following :

Number of shares purchased (2016) = 50

Purchase price of shares $396.33 per share

Closing price per share four years later = $778.38

A) What did Chadwick pay for all of the shares in 2016?

Purchase price per share × number of shares.

$396.33 × 50 = $19,816.50

B) What was the closing value of all of the shares four years later?

Closing price per share × number of ahaf

=$778.38 × 50

= $38,919

C.) Profit on stock :

$(38,919 - 19,816.50)

= $19,102.5

D) What is his rate of return on his shares when he sold them?

(Current Purchase - initial value) /current price

(778.3 - 396.33) / 396.33

= (381.97 / 396.33) 100%

= 0.9637675

=

3 0
2 years ago
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