Which expression is equivalent to w4−25w2+144

The length of time students needed in order to complete a statistics test followed a distribution that was approximately normal.

Olegator [25]

Answer:

$P(X>60)=P(\frac{X-\mu}{\sigma}>\frac{60-\mu}{\sigma})=P(Z>\frac{60-74}{8})=P(z>-1.75)$

And we can find this probability on this way:

$P(z>-1.75)=1-P(z$

And using the normal standard distribution table or excel and we got:

$P(z>-1.75)=1-P(z$

Step-by-step explanation:

Let X the random variable that represent the length of time student of a population, and for this case we know the distribution for X is given by:

$X \sim N(74,8)$

Where $\mu=74$ and $\sigma=8$

We are interested on this probability

$P(X>60)$

We can solve the problem using the z score formula given by:

$z=\frac{x-\mu}{\sigma}$

If we apply this formula to our probability we got this:

$P(X>60)=P(\frac{X-\mu}{\sigma}>\frac{60-\mu}{\sigma})=P(Z>\frac{60-74}{8})=P(z>-1.75)$

And we can find this probability on this way:

$P(z>-1.75)=1-P(z$

And using the normal standard distribution table or excel and we got:

$P(z>-1.75)=1-P(z$

4 0

3 years ago

suppose you have 1000 gallons of gasoline 20% is premium and 80% is regular how much premium gas needs to be added to bring the

Rzqust [24]

20% of 1000 gal = 200 gal of premium gasoline

80% of 1000 gal = 800 gal of regular gasoline

x = volume of premium gasoline that you need to add to the current mixture

60% of the new mixture is supposed to be premium gasoline. The new mixture would have a total volume of (1000 + x) gal, and in this total, you'd have (200 + x) gal of premium gasoline. So

$\dfrac{200+x}{1000+x}=0.60\implies200+x=600+0.60x$

$\implies400=0.40x\implies x=1000$

You'd need to add 1000 gal of premium gasoline to get a mixture of 60% premium.

5 0

3 years ago

X=2y-4 7x+5y=-66 solve by elimination

Alexxandr [17]

Answer:

{x,y}={-8,-2}

Step-by-step explanation:

[1] x = 2y - 4

Plug this in for variable x in equation [2]

[2] 7•(2y-4) + 5y = -66

[2] 19y = -38

Solve equation [2] for the variable y

[2] 19y = - 38

[2] y = - 2

By now we know this much :

x = 2y-4

y = -2

Use the y value to solve for x

x = 2(-2)-4 = -8

3 0

3 years ago

What is the seventh term in the arithmetic sequence defined by the explicit formula an=5n+3?What is the seventh term in the arit

babymother [125]

A7 = 5*7+3 = 38.

Just sub in n = 7 and you will get it.

8 0

4 years ago

Read 2 more answers

Hhh I’m very bad at math

barxatty [35]

Answer:

See below;

Step-by-step explanation:

21 . Consider an exponential function;

$Exponential Function in Form - y = a * b^x, where, a - start value, b - growth factor, x - time,\\\\Now y = f ( x ), in Other Words,\\p ( t ) = 300 * ( 0.5 )^t - Given,\\\\Through Substitution - f ( x ) = p ( t ), a = 300, b = 0.5, x = t,\\\\Conclusion ; 300 - ( start value ) - Starting Amount of Milligrams of Compound,\\0.5 - Milligrams Compound Decreases by$

<em>Solution; Provided Directly Above</em>

3 0

3 years ago