1. A jet travelled 640 miles in 2.5 hours. How far does it travel in 1 hour?

Jay's hair grows about 8 inches each year. Write a function that describes the length l in inches that Jay's hair will grow for

xeze [42]

Answer:

l=8k

Step-by-step explanation:

4 0

2 years ago

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A study of long-distance phone calls made from General Electric Corporate Headquarters in Fairfield, Connecticut, revealed the l

Katena32 [7]

Answer:

(a) The fraction of the calls last between 4.50 and 5.30 minutes is 0.3729.

(b) The fraction of the calls last more than 5.30 minutes is 0.1271.

(c) The fraction of the calls last between 5.30 and 6.00 minutes is 0.1109.

(d) The fraction of the calls last between 4.00 and 6.00 minutes is 0.745.

(e) The time is 5.65 minutes.

Step-by-step explanation:

We are given that the mean length of time per call was 4.5 minutes and the standard deviation was 0.70 minutes.

Let X = the length of the calls, in minutes.

So, X ~ Normal( $\mu=4.5,\sigma^{2} =0.70^{2}$ )

The z-score probability distribution for the normal distribution is given by;

Z = $\frac{X-\mu}{\sigma}$ ~ N(0,1)

where, $\mu$ = population mean time = 4.5 minutes

$\sigma$ = standard deviation = 0.7 minutes

(a) The fraction of the calls last between 4.50 and 5.30 minutes is given by = P(4.50 min < X < 5.30 min) = P(X < 5.30 min) - P(X $\leq$ 4.50 min)

P(X < 5.30 min) = P( $\frac{X-\mu}{\sigma}$ < $\frac{5.30-4.5}{0.7}$ ) = P(Z < 1.14) = 0.8729

P(X $\leq$ 4.50 min) = P( $\frac{X-\mu}{\sigma}$ $\leq$ $\frac{4.5-4.5}{0.7}$ ) = P(Z $\leq$ 0) = 0.50

The above probability is calculated by looking at the value of x = 1.14 and x = 0 in the z table which has an area of 0.8729 and 0.50 respectively.

Therefore, P(4.50 min < X < 5.30 min) = 0.8729 - 0.50 = 0.3729.

(b) The fraction of the calls last more than 5.30 minutes is given by = P(X > 5.30 minutes)

P(X > 5.30 min) = P( $\frac{X-\mu}{\sigma}$ > $\frac{5.30-4.5}{0.7}$ ) = P(Z > 1.14) = 1 - P(Z $\leq$ 1.14)

= 1 - 0.8729 = 0.1271

The above probability is calculated by looking at the value of x = 1.14 in the z table which has an area of 0.8729.

(c) The fraction of the calls last between 5.30 and 6.00 minutes is given by = P(5.30 min < X < 6.00 min) = P(X < 6.00 min) - P(X $\leq$ 5.30 min)

P(X < 6.00 min) = P( $\frac{X-\mu}{\sigma}$ < $\frac{6-4.5}{0.7}$ ) = P(Z < 2.14) = 0.9838

P(X $\leq$ 5.30 min) = P( $\frac{X-\mu}{\sigma}$ $\leq$ $\frac{5.30-4.5}{0.7}$ ) = P(Z $\leq$ 1.14) = 0.8729

The above probability is calculated by looking at the value of x = 2.14 and x = 1.14 in the z table which has an area of 0.9838 and 0.8729 respectively.

Therefore, P(4.50 min < X < 5.30 min) = 0.9838 - 0.8729 = 0.1109.

(d) The fraction of the calls last between 4.00 and 6.00 minutes is given by = P(4.00 min < X < 6.00 min) = P(X < 6.00 min) - P(X $\leq$ 4.00 min)

P(X < 6.00 min) = P( $\frac{X-\mu}{\sigma}$ < $\frac{6-4.5}{0.7}$ ) = P(Z < 2.14) = 0.9838

P(X $\leq$ 4.00 min) = P( $\frac{X-\mu}{\sigma}$ $\leq$ $\frac{4.0-4.5}{0.7}$ ) = P(Z $\leq$ -0.71) = 1 - P(Z < 0.71)

= 1 - 0.7612 = 0.2388

The above probability is calculated by looking at the value of x = 2.14 and x = 0.71 in the z table which has an area of 0.9838 and 0.7612 respectively.

Therefore, P(4.50 min < X < 5.30 min) = 0.9838 - 0.2388 = 0.745.

(e) We have to find the time that represents the length of the longest (in duration) 5 percent of the calls, that means;

P(X > x) = 0.05 {where x is the required time}

P( $\frac{X-\mu}{\sigma}$ > $\frac{x-4.5}{0.7}$ ) = 0.05

P(Z > $\frac{x-4.5}{0.7}$ ) = 0.05

Now, in the z table the critical value of x which represents the top 5% of the area is given as 1.645, that is;

$\frac{x-4.5}{0.7}=1.645$

${x-4.5}{}=1.645 \times 0.7$

x = 4.5 + 1.15 = 5.65 minutes.

SO, the time is 5.65 minutes.

7 0

3 years ago

Select the statements that are true based on the following given information. D = {x | x is a whole number} E = {x | x is a perf

likoan [24]

<h3>2 Answers: Choice C and Choice D</h3>

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Explanation:

Let's write the roster notation of each set

D = {0, 1, 2, 3, ...} the dots indicate the pattern goes on forever

E = {0, 1, 4, 9, 16, 25} = list of perfect squares smaller than 36

F = {20, 22, 24, 26, 28, 30} = even numbers between 20 and 30

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If we intersect sets D and E, we're looking for what numbers are in both sets at the same time. Therefore, D ∩ E = {0, 1, 4, 9, 16, 25} which is the exact same as set E. This is because all of set E is inside of set D. We say that set E is a subset of set D. So, D ∩ E = E.

Choice A is very close to being true. The problem is that 25 is missing from the set {1,4,9,16}. So this is why choice A is false.

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Now let's intersect sets D and F. The numbers they have in common are {20, 22, 24, 26, 28, 30} which is exactly what set F is. So set F is a subset of set D. We can write D ∩ F = F in much the same way we can say D ∩ E = E.

D ∩ F = {12,14,16,18} is not true. A number like 12 is not between 20 and 30, so it cannot be in set F.

Choice B is false so we cross it off the list.

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Choice C is true and here's why

D ∪ (E ∩ F) is the same as saying D ∪ G where G is the set of intersecting E and F together. In other words, G = E ∩ F

We don't really need to even worry about sets E, F or G. All that matters here is set D.

When we write D ∪ (E ∩ F) or D ∪ G, we're saying "a number is in set D, or it is in set G". If it is in D, then it's a whole number. Otherwise, it's in a subset of whole numbers.

Overall, D ∪ G and D ∪ (E ∩ F) form the entire set of whole numbers.

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Choice D is true.

E and F have nothing in common

E = {0, 1, 4, 9, 16, 25}

F = {20, 22, 24, 26, 28, 30}

So intersecting them leads to the empty set. This is the set with nothing inside it, not even 0.

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Choice F is false

These two sets below

E = {0, 1, 4, 9, 16, 25}

F = {20, 22, 24, 26, 28, 30}

union together to get

H = {0,1,4,9,16,20,22,24,25,26,28,30}

just toss all of the numbers together into one big set

Notice how each of these numbers are whole numbers, so they are part of set D. This means set H is also a subset of set D.

When we intersect sets D and H, we end up with set H. We do not simply end up with the set with 25 only inside it.

6 0

3 years ago

The radius of a circle is 19 km what is the circles area using 3.14 for pie

Sholpan [36]

Answer:

1133.54 or 361 pi

Step-by-step explanation:

19^2*pi

5 0

2 years ago

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{4x+2y=10 y=2x-1 What is the value of x+y A.3.125 B.2 C.4.5 D.3.5

Evgen [1.6K]

Answer:

D.3.5

Step-by-step explanation:

4x+2y=10(given)

2x+y=5

y=5-2x-----(1)

y=2x-1------(2)(given)

Since the left side of the equations are the the same,

5-2x=2x-1

4x=6

x=1.5

Sub x=1.5 into eq(1),

y = 5-2(1.5) = 5-3 = 2

so, x+y = 1.5+2 = 3.5

8 0

2 years ago

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