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emmasim [6.3K]
3 years ago
8

What is -1/2(-1) put in to a fravtion

Mathematics
1 answer:
Elodia [21]3 years ago
4 0
Answer
-1/2 x -1 = 1/2
You might be interested in
a baseball player gets a hit 40% of the time if the weather is good but only 20% off the time if it is not good weather. The wea
rosijanka [135]

Answer: The probability of the player getting a hit is 0.214.

Step-by-step explanation:

Since we have given that

Probability  that a baseball player gets a hit if the weather is good = 40% = 0.4

Probability that a baseball player gets a hit if the weather is not good = 20% = 0.2

Probability of good weather = 7% = 0.07

Probability of not good weather = 100-7 = 93% = 0.93

According to question, the probability of the player getting hit is given by

0.4\times 0.07+0.2\times 0.93\\\\=0.214

Hence, the probability of the player getting a hit is 0.214.

8 0
3 years ago
ASK YOUR TEACHER An article reported that for a sample of 42 kitchens with gas cooking appliances monitored during a one-week pe
xxMikexx [17]

Answer:

654.16-2.02\frac{165.23}{\sqrt{42}}=602.66    

654.16+2.02\frac{165.23}{\sqrt{42}}=705.66    

So on this case the 95% confidence interval would be given by (602.66;705.66)

Step-by-step explanation:

Previous concepts

A confidence interval is "a range of values that’s likely to include a population value with a certain degree of confidence. It is often expressed a % whereby a population means lies between an upper and lower interval".

The margin of error is the range of values below and above the sample statistic in a confidence interval.

Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".

\bar X=654.16 represent the sample mean

\mu population mean (variable of interest)

s=165.23 represent the sample standard deviation

n=42 represent the sample size  

Solution to the problem

The confidence interval for the mean is given by the following formula:

\bar X \pm t_{\alpha/2}\frac{s}{\sqrt{n}}   (1)

In order to calculate the critical value t_{\alpha/2} we need to find first the degrees of freedom, given by:

df=n-1=42-1=41

Since the Confidence is 0.95 or 95%, the value of \alpha=0.05 and \alpha/2 =0.025, and we can use excel, a calculator or a table to find the critical value. The excel command would be: "=-T.INV(0.025,41)".And we see that t_{\alpha/2}=2.02

Now we have everything in order to replace into formula (1):

654.16-2.02\frac{165.23}{\sqrt{42}}=602.66    

654.16+2.02\frac{165.23}{\sqrt{42}}=705.66    

So on this case the 95% confidence interval would be given by (602.66;705.66)    

7 0
3 years ago
Determine the sample size needed to construct a 90% confidence interval to estimate the population proportion when p = 0.65 and
WINSTONCH [101]

Answer:

n=170

Step-by-step explanation:

1) Notation and definitions

n random sample taken (variable of interest)

\hat p=0.65 estimated proportion.

p true population

A confidence interval is "a range of values that’s likely to include a population value with a certain degree of confidence. It is often expressed a % whereby a population means lies between an upper and lower interval".  

The margin of error is the range of values below and above the sample statistic in a confidence interval.  

Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".  

The population proportion have the following distribution

p \sim N(p,\sqrt{\frac{\hat p(1-\hat p)}{n}})

In order to find the critical value we need to take in count that we are finding the interval for a proportion, so on this case we need to use the z distribution. Since our interval is at 90% of confidence, our significance level would be given by \alpha=1-0.90=0.1 and \alpha/2 =0.05. And the critical value would be given by:

z_{\alpha/2}=\pm 1.64

The margin of error for the proportion interval is given by this formula:  

ME=z_{\alpha/2}\sqrt{\frac{\hat p (1-\hat p)}{n}}    (a)  

And on this case we have that ME =\pm 0.06 and we are interested in order to find the value of n, if we solve n from equation (a) we got:  

n=\frac{\hat p (1-\hat p)}{(\frac{ME}{z})^2}   (b)  

And replacing into equation (b) the values from part a we got:

n=\frac{0.65(1-0.65)}{(\frac{0.06}{1.64})^2}=169.968  

And rounded up we have that n=170

6 0
3 years ago
Ella’s Cafe uses 3/10 of a bag of coffee every day. For how many days will 2 7/10 bags of coffee last? Simplify your answer and
Vilka [71]
It should last for 9 days.


7 0
3 years ago
Read 2 more answers
Identify the constant of proportionality from the table.
ivann1987 [24]

Answer:

The constant of proportionality is 3.

Step-by-step explanation:

6/2 is 3 and so on.

Correct me if I'm wrong

3 0
2 years ago
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