On a number line does a negative number go the bottom or top

Calculate the sample mean and sample variance for the following frequency distribution of heart rates for a sample of American a

spin [16.1K]

Answer:

$Mean = 68.9$

$s^2 =18.1$ --- Variance

Step-by-step explanation:

Given

$\begin{array}{cccccc}{Class} & {51-58} & {59-66} & {67-74} & {75-82} & {83-90} \ \\ {Frequency} & {6} & {3} & {11} & {13} & {4} \ \end{array}$

Solving (a): Calculate the mean.

The given data is a grouped data. So, first we calculate the class midpoint (x)

For 51 - 58.

$x = \frac{1}{2}(51+58) = \frac{1}{2}(109) = 54.5$

For 59 - 66

$x = \frac{1}{2}(59+66) = \frac{1}{2}(125) = 62.5$

For 67 - 74

$x = \frac{1}{2}(67+74) = \frac{1}{2}(141) = 70.5$

For 75 - 82

$x = \frac{1}{2}(75+82) = \frac{1}{2}(157) = 78.5$

For 83 - 90

$x = \frac{1}{2}(83+90) = \frac{1}{2}(173) = 86.5$

So, the table becomes:

$\begin{array}{cccccc}{x} & {54.5} & {62.5} & {70.5} & {78.5} & {86.5} \ \\ {Frequency} & {6} & {3} & {11} & {13} & {4} \ \end{array}$

The mean is then calculated as:

$Mean = \frac{\sum fx}{\sum f}$

$Mean = \frac{54.5*4+62.5*3+70.5*11+78.5*13+86.5*4}{6+3+11+13+4}$

$Mean = \frac{2547.5}{37}$

$Mean = 68.9$ -- approximated

Solving (b): The sample variance:

This is calculated as:

$s^2 =\frac{\sum (x - \overline x)^2}{\sum f - 1}$

So, we have:

$s^2 =\frac{(54.5-68.9)^2+(62.5-68.9)^2+(70.5-68.9)^2+(78.5-68.9)^2+(86.5-68.9)^2}{37 - 1}$

$s^2 =\frac{652.8}{36}$

$s^2 =18.1$ -- approximated

5 0

2 years ago

i need help please! I think I know the answer but for some reason my brain's telling me that it's wrong so if someone could expl

Ivenika [448]

Considering the slopes of the segments, the correct option is:

D. No, because the triangle ABC doesn't have a pair of perpendicular sides.

<h3>When are lines parallel, perpendicular or neither?</h3>

The slope, given by change in y divided by change in x, determines if the lines are parallel, perpendicular, or neither, as follows:

If they are equal, the lines are parallel.

If their multiplication is of -1, they are perpendicular.

Otherwise, they are neither.

Here, we have to find if there are perpendicular segments, that is, if two slopes multiplied have a value of -1, then:

mAB = (-7 - 9)/(11 - 1) = -8/5.

mAC = (3 - 9)/(-9 - 1) = 3/5.

mBC = (3 - (-7))/(-9 - 11) = -1/2.

No sides are perpendicular, hence option D is correct.

More can be learned about slopes at brainly.com/question/20847660

#SPJ1

6 0

1 year ago

The table shows the relationship y = kx.

sammy [17]

Answer: it’s 1/5

Step-by-step explanation:

6 0

3 years ago

A taxi travels 25 km east of airport. Then it travels from that point to a point that is 40 km west of the airport. Finally the

Marizza181 [45]

The answer is: " 95 km " .
__________________________________________________
Explanation:
__________________________________________________

 ("airport")
• {Step 1): " 25 km east " •
│===============================> │

• {Step 2): " 40 km west ["of that point"] " ; • │<==========================================│

 • {Step 3: [back to airport] = " (40 km − 25 km) " ;

 • ("airport").
│=======>│
 _________________________________________________

 Note: To find "total distance traveled:

" 40 km + (40 km) + (40 km − 25 km) " ;

= " 40 km + (40 km) + (15 km) " ;

= " 40 km + 40 km + (15 km) " ;

= 80 km + 15 km ;

= 95 km .
____________________________________________________

The answer is: " 95 km " .
____________________________________________________

4 0

3 years ago

Suppose that your business is operating at the 4.5-Sigma quality level. If projects have an average improvement rate of 50% annu

Luda [366]

Answer:

11.75 years

Step-by-step explanation:

If we ignore the fact that "6-sigma" quality means the error rate corresponds to about -4.5σ (3.4 ppm) and simply go with ...

P(z ≤ -6) ≈ 9.86588×10^-10

and

P(z ≤ -4.5) ≈ 3.39767×10^-6

the ratio of these error rates is about 0.000290372. We're multiplying the error rate by 0.5 each year, so we want to find the power of 0.50 that gives this value:

0.50^t = 0.000290372

t·log(0.50) = log(0.00290372) . . . . take logarithms

t = log(0.000290372)/log(0.50) ≈ -3.537045/-0.301030

t ≈ 11.75

It will take about 11.75 years to achieve Six Sigma quality (0.99 ppb error rate).

_____

Comment on Six Sigma

A 3.4 ppm error rate is customarily associated with "Six Sigma" quality. It assumes that the process may have an offset from the mean of up to 1.5 sigma, so the "six sigma" error rate is P(z ≤ (1.5 -6)) = P(z ≤ -4.5) ≈ 3.4·10^-6.

Using that same criteria for the "4.5-Sigma" quality level, we find that error rate to be P(z ≤ (1.5 -4.5)) = P(z ≤ -3) ≈ 1.35·10^-3.

Then the improvement ratio needs to be only 0.00251699, and it will take only about ...

t ≈ log(0.00251699)/log(0.5) ≈ 8.6 . . . . years

5 0

3 years ago