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shusha [124]
3 years ago
5

alex and Lara have $21.00 each to spend at a book fair, where all students receive a 35% discount. They both want to purchase a

copy of the same book, which normally sells for $28.50 plus 10% sales tax. To check if he has enough to purchase the book, Alex takes 35% of $28.50 and subtracts that amount from the normal price. He takes 10% of the discounted selling price and adds it back to find the purchase amount. Lara takes 65% of the normal purchase price and then computes 110% of the reduced price. Is Alex correct? Is Lara correct? Do they have enough money to purchase the book? Explain your answer using complete sentences, and show your work.
Mathematics
1 answer:
storchak [24]3 years ago
6 0
Alex is correct the book would cost $18.52 before taxes adding 10% tax the book would cost an additional $1.85 for a total of $20.37. This would be just under the $21.00 that both Alex and Laura had to spend. Laura tried to combined the 35% discount which you cannot do. So yes they both would be able to purchase the book.
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How much energy would a 15,000 g block of ice need to absorb in order to
Sergeu [11.5K]

Answer:

The energy a 15,000 g block of ice will absorb in order to melt is 4995 kJ

Step-by-step explanation:

The question relates to the latent heat of fusion of ice, that is the heat absorbed by the solid ice to convert it to liquid water without changing its temperature.

The formula for the energy required to melt the ice is presented as follows;

Energy required = Mass, m × Latent heat of fusion, L_f, of ice

Hence, the mass, m, of the ice = 15,000 g

Latent heat of fusion, L_f, of ice = 333 J/g

Therefore;

Energy required = 15,000 g × 333 J/g = 4995000 J

Hence;

The energy a 15,000 g block of ice will absorb in order to melt = 4995000 J

1000 J = 1 kJ

1 J = 1/1000 kJ

Therefore, 4995000 J = (4995000 J)/(1000 J/kJ) = 4995 kJ.

Which gives;

The energy a 15,000 g block of ice will absorb in order to melt = 4995 kJ.

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2 years ago
What’s the answer to this problem?
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3 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
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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.

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Hey there! I'm happy to help!

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A psychologist treats 16 patients and records the number of sessions required to complete a behavioral therapy treatment for eac
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Hence, the standard deviation for these data is 7.1 sessions

In statistics, the standard deviation is a measure of the volatility or variance of a set of values. [1] A low standard deviation indicates that the values ​​tend to be close to the mean of the set (also known as the mean), and a high standard deviation indicates that the values ​​are more widely distributed. indicate.

Standard deviation can be abbreviated as SD, and in mathematical texts and equations, it is most commonly represented by the Greek lower σ (sigma) for population standard deviation or the Latin letter s for sample standard deviation. It is a target.

The standard deviation of a random variable, sample, population, dataset, or probability distribution is the square root of its variance. It's algebraically simple, but it's actually less robust than mean absolute deviation. A useful property of standard deviation is that, unlike variance, it is expressed in the same units as the data.

Expression

\ sigma = {\ sqrt {\ frac {\ sum (x_ {i}-{\ mu}) ^ {2}} {N}}}

\ sigma = Population standard deviation

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x_i = Arbitrary value from population

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Learn more about standard deviation   here: brainly.com/question/475676

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