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mrs_skeptik [129]
3 years ago
9

The heights of a group of girls are normally distributed with a mean of 66 inches. If 95% of the heights of these girls are betw

een 63 and 69 inches, what is the standard deviation for this group.
Mathematics
1 answer:
alisha [4.7K]3 years ago
6 0

Answer:

The standard deviation is 1.5 inches.

Step-by-step explanation:

For a normal curve, we have that the area between the mean and the mean plus two times the standard deviation is something around 47.5%

Then the area between the mean minus two times the standard deviation and the mean plus two times the standard deviation is equal to the 95%.

the mean is 66

if the standard deviation is x, we have that:

66 + 2*x = 69

66 - 2*x = 63

then we can find that:

2*x = 66 - 63 = 3

x = 3/2 = 1.5

The standard deviation is 1.5 inches.

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at Michaels auto shop, it takes him 15 minutes to do an oil change and 24 minutes to do a tire change. let x be the number of oi
Roman55 [17]

Answer:

Step-by-step explanation:

At Susan's auto shop, it takes her 12 minutes to do an oil change and 18 minutes to do a tire change. Let x be the number of oil changes she does. Let y be the number of tire changes she does.

Using the values and variables given, write an inequality describing how many oil changes and tire changes Susan can do in less than 3 hours (180 minutes).

Answer provided by our tutors

The total time that Susan needs to change x oil changes and y tire changes is less than 180 min.

The time needed for x oil changes is 12 * x.

The time needed for y tire changes is 18 * y.

The total time is the sum of the above times and needs to be less than 180 that is

12 * x + 18 * y < 180 divide both sides of equation by 6

12/6 * x + 18/6*y < 180/6

2*x + 3*y < 30

2*x < 30 - 3*y divide both sides by 2 to get the inequality for x

x < 30/2 - 3/2*y = 15 - 1.5 y < 15 that is x < = 15

2*x + 3*y < 30

3*y < 30 - 2*x divide both sides by 3 to get the inequality for y

y < 30/3 - 2/3 *x = 10 - 2/3*x < 10 that is y < = 10

Also we can write x + y < x+ 3/2 * y < 15.

Susan can do not more then 5 oil changes and not more then 10 tire changes or all together she can do not more then 15 total of oil and tire changes.

Just do this problem but with Michael

8 0
2 years ago
when Jeremy surveyed Thirty seventh grade students at the community pool he found that to a 15 had not read at least one book du
Anettt [7]

200 * 2/15 = the number of students that didn't read any books. This is 26.6, so 40 is not a good estimate 40 students is 20 percent versus 26 being approximately 13 percent.


hope this helps i tryed

ur welcome(;

have a great day

8 0
3 years ago
The diameter of a circle measures 28 mm. What is the circumference of the circle?
Papessa [141]

Answer:

C = 87.92 mm

General Formulas and Concepts:

<u>Symbols</u>

  • π (pi) ≈ 3.14

<u>Pre-Algebra</u>

Order of Operations: BPEMDAS

  1. Brackets
  2. Parenthesis
  3. Exponents
  4. Multiplication
  5. Division
  6. Addition
  7. Subtraction
  • Left to Right<u> </u>

<u>Geometry</u>

Circumference Formula: C = πd

  • <em>C</em> is circumference
  • <em>d</em> is diameter

Step-by-step explanation:

<u>Step 1: Define</u>

Diameter <em>d</em> = 28 mm

<u>Step 2: Solve</u>

  1. Substitute in variables [Circumference Formula]:                                          C = 3.14(28 mm)
  2. [Circumference] Multiply:                                                                                 C = 87.92 mm
8 0
3 years ago
Help??
KatRina [158]
It’s 5h because you aren’t adding homework, subtracting homework or dividing homework
4 0
3 years ago
Read 2 more answers
Can someone pls help me with these equations
Zielflug [23.3K]

Answer:

1. y = -2x+5

2. y = 3/4 - 3

3. intercept = -5 slope =  4/3

4. intercept = 1 slope = -1/2

5 0
3 years ago
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