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3 years ago

What is (- 4/5) - 7/8

Mathematics

1 answer:

mixer [17]3 years ago

5 0

First, find the lowest common multiple of 5 and 8 and it is 40.

-32/40 - 35/40

= -67/40

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Erica had 6 coins in her coin collection. She goes to a coin show and buys some more coins. How many coins does she have now?

goldfiish [28.3K]

Answer:

6+x with x equalling the amount of coins bought if that is what you were looking for

Step-by-step explanation:

if you want to make and equation out of this you don't know the amount of coins she bought so you use a variable (x) to replace that unknown number then since it says she bought more she is adding more to her collection which means it would be an addition problem, leaving you with 6+x for your final answer

5 0

3 years ago

5. Carlotta's Beauty Supply store sells two brands of bar soap. A 6 pack of Brand A costs

vekshin1

I think it would be be because you’re actually saving a little bit more amount of money you’re paying a dollar and would say two cent for each bar

6 0

2 years ago

How many students must be randomly selected to estimate the mean weekly earnings of students at one college? We want 95% confide

kari74 [83]

Answer:

The sample of students required to estimate the mean weekly earnings of students at one college is of size, 3458.

Step-by-step explanation:

The (1 - α)% confidence interval for population mean (μ) is:

$CI=\bar x\pm z_{\alpha/2}\times \frac{\sigma}{\sqrt{n}}$

The margin of error of a (1 - α)% confidence interval for population mean (μ) is:

$MOE=z_{\alpha/2}\times \frac{\sigma}{\sqrt{n}}$

The information provided is:

σ = $60

MOE = $2

The critical value of z for 95% confidence level is:

$z_{\alpha/2}=z_{0.05/2}=z_{0.025}=1.96$

Compute the sample size as follows:

$MOE=z_{\alpha/2}\times \frac{\sigma}{\sqrt{n}}$

$n=[\frac{z_{\alpha/2}\times \sigma }{MOE}]^{2}$

$=[\frac{1.96\times 60}{2}]^{2}$

$=3457.44\\\approx 3458$

Thus, the sample of students required to estimate the mean weekly earnings of students at one college is of size, 3458.

8 0

2 years ago

Bad gums may mean a bad heart. Researchers discovered that 82% of people who have suffered a heart attack had periodontal diseas

saveliy_v [14]

Answer:

37.27% probability that he or she will have a heart attack.

Step-by-step explanation:

Bayes Theorem:

Two events, A and B.

$P(B|A) = \frac{P(B)*P(A|B)}{P(A)}$

In which P(B|A) is the probability of B happening when A has happened and P(A|B) is the probability of A happening when B has happened.

In this question:

Event A: Periodontal disease

Event B: Heart attack

Researchers discovered that 82% of people who have suffered a heart attack had periodontal disease, an inflammation of the gums.

This means that $P(A|B) = 0.82$

Only 33% of healthy people have this disease.

This means that $P(A) = 0.33$

Suppose that in a certain community heart attacks are quite rare, occurring with only 15% probability.

This means that $P(B) = 0.15$

If someone has periodontal disease, what is the probability that he or she will have a heart attack

$P(B|A) = \frac{0.15*0.82}{0.33} = 0.3727$

37.27% probability that he or she will have a heart attack.

6 0

2 years ago

So I don't if I'm right help would be much appreciated

lukranit [14]

Answer:

A is the correct equation

Step-by-step explanation:

3 0

2 years ago