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

Anna [14]

Answer:

a) 0.4452

b) 0.0548

c) 0.0501

d) 0.9145

e) 6.08 minutes or greater

Step-by-step explanation:

We are given the following information in the question:

Mean, μ = 4.7 minutes

Standard Deviation, σ = 0.50 minutes.

We are given that the distribution of length of the calls is a bell shaped distribution that is a normal distribution.

Formula:

$z_{score} = \displaystyle\frac{x-\mu}{\sigma}$

a) P(calls last between 4.7 and 5.5 minutes)

$P(4.7 \leq x \leq 5.5) = P(\displaystyle\frac{4.7 - 4.7}{0.50} \leq z \leq \displaystyle\frac{5.5-4.7}{0.50}) = P(0 \leq z \leq 1.6)\\\\= P(z \leq 1.6) - P(z$

$P(4.7 \leq x \leq 5.5) = 44.52\%$

b) P(calls last more than 5.5 minutes)

$P(x > 5.5) = P(z > \displaystyle\frac{5.5-4.7}{0.50}) = P(z > 1.6)\\\\P( z > 1.6) = 1 - P(z \leq 1.6)$

Calculating the value from the standard normal table we have,

$1 - 0.9452 = 0.0548 = 5.48\%\\P( x > 5.5) = 5.48\%$

c) P( calls last between 5.5 and 6 minutes)

$P(4.7 \leq x \leq 5.5) = P(\displaystyle\frac{5.5 - 4.7}{0.50} \leq z \leq \displaystyle\frac{6-4.7}{0.50}) = P(1.6 \leq z \leq 2.6)\\\\= P(z \leq 2.6) - P(z$

$P(5.5 \leq x \leq 6) = 5.01\%$

d) P( calls last between 4 and 6 minutes)

$P(4 \leq x \leq 6) = P(\displaystyle\frac{4 - 4.7}{0.50} \leq z \leq \displaystyle\frac{6-4.7}{0.50}) = P(-1.4 \leq z \leq 2.6)\\\\= P(z \leq 2.6) - P(z$

$P(4 \leq x \leq 6) = 91.45\%$

e) We have to find the value of x such that the probability is 0.03.

P(X > x)

$P( X > x) = P( z > \displaystyle\frac{x - 4.7}{0.50})=0.03$

$= 1 -P( z \leq \displaystyle\frac{x - 4.7}{0.50})=0.03$

$=P( z \leq \displaystyle\frac{x - 4.7}{0.50})=0.997$

Calculation the value from standard normal z table, we have,

P(z < 2.75) = 0.997

$\displaystyle\frac{x - 4.7}{0.50} = 2.75\\x = 6.075 \approx 6.08$

Hence, the call lengths must be 6.08 minutes or greater for them to lie in the highest 3%.

8 0

3 years ago

Determine the intercepts of the line.

a_sh-v [17]

Answer:

y-intercept: -18

x-intercept: 9/4

Step-by-step explanation:

Substitute x = 0, we find that y = -18 i.e. the y-intercept is -18.

Substitute y = 0, we find that x = 9/4 i.e. the x-intercept is 9/4.

7 0

3 years ago

The Area of the circles

NNADVOKAT [17]

Answer:

254.4 in²

Step-by-step explanation:

Area of a circle is given by the formula:

$\pi r^{2}$

Our radius is 9 so we substitute this into the equation:

π(9)² = 81π

81π = 254.4 in²

6 0

2 years ago

Read 2 more answers

Write the equation of a line that is parallel to y=1/2x−4y and that passes through the point (9,−6)

lara [203]

Answer:

the desired equation is

y = (1/2)x - 21/2

Step-by-step explanation:

Looks as tho' you may have typed in an extra 'y' here. I will proceed under the assumption that you meant y = (1/2)x - 4. This line has a slope of 1/2.

Any line parallel to it also has a slope of m = 1/2.

Start by replacing y, x, m and b in y = mx + b with the knowns:

y = mx + b becomes -6 = (1/2)(9) + b.

Clear this of fractions by multiplying all 3 terms by 2:

-12 = 9 + 2b, or:

-21 = 2b. Dividing both sides by 2 results in b = -21/2.

Thus, the desired equation is

y = (1/2)x - 21/2

8 0

3 years ago

How much time does Maria spend online on Saturday?HELP ME PLZZZZZZZZZZZZ

Fiesta28 [93]

Answer:

75%

Step-by-step explanation:

4 0

4 years ago