Write the first four multiples of each number. 1. 3 2. 4 3. 8 4. 15

A normal distribution curve, where x = 70 and σ = 15, was created by a teacher using her students’ grades. What information abou

alexira [117]

The correct answer is:

We can conclude that 68% of the scores were between 55 and 85; 95% of the scores were between 40 and 100; and 99.7% of the scores were between 25 and 100.

Explanation:

The empirical rule tells us that in a normal curve, 68% of data lie within 1 standard deviation of the mean; 95% of data lie within 2 standard deviations of the mean; and 99.7% of data lie within 3 standard deviations of the mean.

The mean is 70 and the standard deviation is 15. This means 1 standard deviation below the mean is 70-15 = 55 and one standard deviation above the mean is 70+15 = 85. 68% of data will fall between these two scores.

2 standard deviations below the mean is 70-15(2) = 40 and two standard deviations above the mean is 70+15(2) = 100. 95% of data will fall between these two scores.

3 standard deviations below the mean is 70-15(3) = 25 and three standard deviations above the mean is 70+15(3) = 115. However, a student cannot score above 100%; this means 99.7% of data fall between 25 and 100.

4 0

3 years ago

Read 2 more answers

Can you have a triangle with sides 6, 7, and 2?

Alexandra [31]

I believe yes, as long as a triangle has 3 sides it is indeed a triangle

5 0

3 years ago

This is Daniela’s work to solve the equation 13 x + 42 = 276.

Yuliya22 [10]

Answer:
Subtraction property of equality.

4 0

3 years ago

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On rainy days, Izzy goes from his house to the school by running 1.2 miles on West St, then makes a 90º turn and runs 0.5 miles

OlgaM077 [116]

Answer:

a) It will take Izzy 0.226 hours = 13.6 minutes = 13 minutes 36 seconds to run to school on dashed days.

b) Izzy runs 1.30 miles on dry days.

c) Izzy saves 3 minutes and 12 seconds cutting through the woods.

Step-by-step explanation:

This problem can be solved by a simpe rule of three problem.

a) On rainy days, she runs 1.2 + 0.5 = 1.7 miles.

The problem states that for rainy days, she runs 7.5 miles per hour. We know that in a hour, Izzy will run 7.5 miles. We want to know how long it takes for her to run 1.7 miles. So

1 hour - 7.5 miles

x hours - 1.7 miles

7.5x = 1.7

$x = \frac{1.7}{7.5}$

x = 0.226 hours

It will take Izzy 0.226 hours = 13.6 minutes = 13 minutes 36 seconds to run to school on dashed days.

b) Now we have a right triangle, where the sides are the 1.2 miles and the 0.5miles, and the path through the woods x is the hypotenuse.

So, we apply the pythagorean theorem.

$x^{2} = (1.2)^{2} + (0.5)^{2}$

$x^{2} = 1.44 + 0.25$

$x^{2} = 1.69$

$x = 1.30$

So, Izzy runs 1.30 miles on dry days.

c) The first step for this question is knowing how long it takes for Izzy to run 1.30 miles at 7.50 miles a hour. So:

1 hour - 7.50 miles

x hours = 1.30 miles

7.50x = 1.30

$x = \frac{1.3}{7.5}$

x = 0.173 hours

So, it takes Izzy 0.173 hours = 10.4 minutes = 10 minutes 24 seconds to run through the woods.

13' 36''

-10' 24''

3' 12''

Izzy saves 3 minutes and 12 seconds cutting through the woods.

5 0

3 years ago

This is a System Of Equations and I'd like it to get solved by the Elimination or Substitution Method.x+2y=83x+5y=8

Sonbull [250]

Answer:

x=133 y=-25

Step-by-step explanation:

I'll do both ways for you. So let's start with Substitution:

With the sub method, you have to set both equations equal to each other by setting them equal to the same variable. Since there is no coefficient in front of both x's in both equations, that variable will be easiest to solve for.

x + 2y = 83 & x + 5y = 8

Solve for x.

x = 83 - 2y & x = 8 - 5y

Once you have solved for x, set each equation equal to one another and solve for y now.

83 - 2y = 8 - 5y

Isolate all variables to one side:

83 = 8 - 3y

Now subtract the 8 to fully isolate the y variable:

75 = -3y

Divide by -3:

-25 = y Now that you have your first variable, plug it into one of the original equations and solve for x.

x + 2(-25) = 83

x - 50 = 83

x = 133

Now for the Elimination method. For this method you need to get rid of a variable by either subtracting/adding each equation together. Again, since you can subtract and x from both equations, you will be left with only the y variable to solve:

Put each equation on top of one another and subtract:

x + 2y = 83

- (x + 5y = 8)

The x's will cancel out:

(x - x) + (2y - 5y) = (83 - 8)

Simplify:

-3y = 75

Solve for y

y = -25

Then, plug y = -25 into one of the original equations:

x + 5(-25) = 8

Solve for x:

x - 125 = 8

x = 133

Hope this helps!

8 0

2 years ago

Write the first four multiples of each number.1. 3 2. 43. 8 4. 15