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2 years ago

3. At the start of summer, Ben has $250 . He takes a summer

Mathematics

1 answer:

earnstyle [38]2 years ago

3 0

Answer:

Week 4

Step-by-step explanation:

Ben has $250 in the beginning. He saves $150 per week.

y = 150x + 250

Tim has $1,650 in the beginning. He spends $200 per week.

y = 1650 - 200x

We are trying to find which x-value produces the same y-value for both equations. You can do this by setting both equations equal to each other.

150x + 250 = 1650 - 200x

(150x + 250) + 200x = (1650 - 200x) + 200x

350x + 250 = 1650

(350x + 250) - 250 = (1650) - 250

350x = 1400

(350x)/350 = (1400)/350

x = 4

By week 4, they will have the same amount of money.

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Step-by-step explanation:

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2 years ago

A random sample of 9 wheels of cheese yielded the following weights in pounds has a sample mean of 20.90 and a sample variance o

Ronch [10]

Answer:

$2.002 \leq \sigma^2 \leq 11.365$

Step-by-step explanation:

1) Data given and notation

s represent the sample standard deviation

$s^2$ represent the sample variance

n=9 the sample size

Confidence=90% or 0.90

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 mean or variance 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.

The Chi Square distribution is the distribution of the sum of squared standard normal deviates .

2) Calculating the confidence interval

The confidence interval for the population variance is given by the following formula:

$\frac{(n-1)s^2}{\chi^2_{\alpha/2}} \leq \sigma \frac{(n-1)s^2}{\chi^2_{1-\alpha/2}}$

On this case we need to find the sample standard deviation with the following formula:

$s=sqrt{\frac{\sum_{i=1}^9 (x_i -\bar x)^2}{n-1}}
The sample variance given was [tex]s^2=3.45$

The next step would be calculate the critical values. First we need to calculate the degrees of freedom given by:

$df=n-1=9-1=8$

Since the Confidence is 0.90 or 90%, the value of $\alpha=0.1$ and $\alpha/2 =0.05$ , and we can use excel, a calculator or a table to find the critical values.