Answer:
The standard deviation of that data set is 3.8
Step-by-step explanation:
The Empirical Rule states that, for a normally distributed random variable:
68% of the measures are within 1 standard deviation of the mean.
95% of the measures are within 2 standard deviation of the mean.
99.7% of the measures are within 3 standard deviations of the mean.
In this problem, we have that:
Mean = 55
95% of the data fall between 47.4 and 62.6. This means that 47.4 is 2 standard deviations below the mean and 62.6 is two standard deviations above the mean.
Using one of these points.
55 + 2sd = 62.6
2sd = 7.6
sd = 7.6/2
sd = 3.8
The standard deviation of that data set is 3.8
<span>A freight train completes its journey of 150 miles 1 hour earlier if its original speed is increased by 5 miles/hour. What is the train’s original speed?
***
let x=original speed
x+5=increased speed
travel time=distance/speed
..
lcd:x(x+5)
150(x+5)-150x=x(x+5)
150x+750-150x=x^2+5x
x^2+5x-750=0
(x-25)(x+30)=0
x=25
What is the train’s original speed? 25 mph</span>
Answer:

And when we apply the limit we got that:

Step-by-step explanation:
Assuming this complete problem: "The following formula for the sum of the cubes of the first n integers is proved in Appendix E. Use it to evaluate the limit . 1^3+2^3+3^3+...+n^3=[n(n+1)/2]^2"
We have the following formula in order to find the sum of cubes:

We can express this formula like this:
![\lim_{n\to\infty} \sum_{n=1}^{\infty}i^3 =\lim_{n\to\infty} [\frac{n(n+1)}{2}]^2](https://tex.z-dn.net/?f=%20%5Clim_%7Bn%5Cto%5Cinfty%7D%20%5Csum_%7Bn%3D1%7D%5E%7B%5Cinfty%7Di%5E3%20%3D%5Clim_%7Bn%5Cto%5Cinfty%7D%20%5B%5Cfrac%7Bn%28n%2B1%29%7D%7B2%7D%5D%5E2)
And using this property we need to proof that: 1^3+2^3+3^3+...+n^3=[n(n+1)/2]^2
![\lim_{n\to\infty} [\frac{n(n+1)}{2}]^2](https://tex.z-dn.net/?f=%20%5Clim_%7Bn%5Cto%5Cinfty%7D%20%5B%5Cfrac%7Bn%28n%2B1%29%7D%7B2%7D%5D%5E2)
If we operate and we take out the 1/4 as a factor we got this:

We can cancel
and we got

We can reorder the terms like this:

We can do some algebra and we got:

We can solve the square and we got:

And when we apply the limit we got that:

Answer:
On a coordinate plane, a parabola opens up
It goes through (negative 3, 0), has a vertex at (negative 0.5, negative 6.25), and goes through (2, 0).
Step-by-step explanation:
f(x) = (x + 3)(x – 2)
We know that parabola opens up since the x^2 term is be positive
it has zeros at x=-3 and x=2
x+3 =0 and x-2 =0 from the zero product property
The vertex is halfway between the zeros
(-3+2)/2 = -1/2
x=-1/2
f(-1/2) = (-1/2+3) (-1/2-2) = 2.5 * -2.5 =-6.25
The vertex is (-1/2, -6.25)
The <u>correct answer</u> is:
0.08.
Explanation:
To calculate the BAC, we first find the amount of alcohol (in grams) of the drinks. In the US, a standard drink has 14 g of alcohol. The man has 2 beers and 1 shot; this is 3 standard drinks:
3*14 = 42
This has 42 g of alcohol.
Next we convert the weight in pounds to grams. We do this by multiplying by 454:
140*454 = 63560
Next we multiply by the gender constant. For men, this is 0.68:
63560(0.68) = 43220.8
We divide the grams of alcohol by this number:
42/43220.8 = 0.000972
Multiply this by 100:
0.000972(100) = 0.0972
This is the BAC right after drinking. To account for the time that has passed, we multiply the number of hours by 0.015:
1(0.015) = 0.015
We subtract this from our immediate BAC:
0.0972-0.015 = 0.0822 ≈ 0.08