The temperature went from 48° to 36° in two hours. What is the percent of decrease in the temperature?

1 point) As reported in "Runner's World" magazine, the times of the finishers in the New York City 10 km run are normally distri

BigorU [14]

Answer:

(a) E (X) = 61 and SD (X) = 9

(b) E (Z) = 0 and SD (Z) = 1

Step-by-step explanation:

The time of the finishers in the New York City 10 km run are normally distributed with a mean,μ = 61 minutes and a standard deviation, σ = 9 minutes.

(a)

The random variable X is defined as the finishing time for the finishers.

Then the expected value of X is:

E (X) = 61 minutes

The variance of the random variable X is:

V (X) = (9 minutes)²

Then the standard deviation of the random variable X is:

SD (X) = 9 minutes

(b)

The random variable Z is the standardized form of the random variable X.

It is defined as: $Z=\frac{X-\mu}{\sigma}$

Compute the expected value of Z as follows:

$E(Z)=E[\frac{X-\mu}{\sigma}]\\=\frac{E(X)-\mu}{\sigma}\\=\frac{61-61}{9}\\=0$

The mean of Z is 0.

Compute the variance of Z as follows:

$V(Z)=V[\frac{X-\mu}{\sigma}]\\=\frac{V(X)+V(\mu)}{\sigma^{2}}\\=\frac{V(X)}{\sigma^{2}}\\=\frac{9^{2}}{9^{2}}\\=1$

The variance of Z is 1.

So the standard deviation is 1.

8 0

3 years ago

Jordan is starting to save $150 to buy a new cell phone. In December, he saved $5. In January, he plans twice as much as he did

-Dominant- [34]

Answer: At the Month May Jordan as able to get enough money to buy the phone.

Work:

December:$5

January:$10

February:$20

March:$40

April:$80

May:$160 <--Answer

____________________________________________________________In the problem Jordan saves $5 at December, then at January Jordan saved $10 which is twice as December's saved money amount. February, Jordan saved $20, which is twice as January's saved money amount. March is $40, which is twice as February's saved money amount. For April it is $80, which is twice as March's money amount, May is $160 which is twice as April's money amount. Or another way to say this is by starting at $5. Then, keep multiplying by 2 for each month until you get $150 or more. When you do, stop at the month that gets you $150 or more. When i did this exact method, I got $160 on the Month of May. $160 is more than enough for Jordan to buy his phone. So the month May is the correct answer where Jordan can get enough money for his phone.

3 0

3 years ago

Read 2 more answers

Can ya help me with the answer

Sergio039 [100]

23.55 feet is your answer

3 0

3 years ago

-12x2 + 45x + 12

bazaltina [42]

Answer:

3(4x + 1)(x - 4) Answer choice B