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hoa [83]
2 years ago
12

If Mark reads 18 pages less per day than originally planned, he will need 5 extra days to finish the book. If he reads 24 pages

less per day, he will need 8 extra days to finish. How many pages does the book have?
PLZ HELP
Mathematics
1 answer:
JulijaS [17]2 years ago
3 0

Answer:

Total number of pages is 540.

Step-by-step explanation:

Let mark read x be he number of pages per day and d be the number of days to finish the book.

Total number of pages = xd

Mark reads 18 pages less per day than originally planned, he will need 5 extra days to finish the book.

(x-18)(d+5)=xd

xd+5x-18d-90=xd

5x-18d=90            .... (1)

He reads 24 pages less per day, he will need 8 extra days to finish.

(x-24)(d+8)=xd

xd+8x-24d-192=xd

8x-24d=192

x-3d=24       ... (2)

Subtract 5 times of equation (2) from equation (1).

5x-18d-5(x-3d)=90-5(24)

5x-18d-5x+15d=90-120

-3d=-30

d=10

Substitute d=10 in equation (1).

5x-18(10)=90  

5x-180=90  

5x=90+180

5x=270

Divide both sides by 5.

x=54

Total number of pages

xd=(54)(10)=540

Therefore , the total number of pages is 540.

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Answer:

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For each phone call, there are only two possible outcomes. Either a sale is made, or it is not. The probability of a sale being made in a call is independent from other calls. So we use the binomial probability distribution to solve this question.

Binomial probability distribution

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b. The probability of making no sales.

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So

E(X) = 12*0.3 = 3.6

The mean number of sales in the two-hour period is 3.6.

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