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malfutka [58]
1 year ago
6

Jen's commute to work requires that she take the blue subway line, then transfer to the red line. the length of the trip on the

blue line has a mean of 18 minutes with a standard deviation of 2 minutes. the red line trip takes 12 minutes with a standard deviation of 1 minute. the waiting time between when she gets off the blue line and her red line train arrives has mean of 10 minutes and a standard deviation of 5 minutes. assume (perhaps unrealistically) that these times are independent random variables. what are the mean and standard deviation of her entire commute?
Mathematics
1 answer:
Brrunno [24]1 year ago
5 0

In order to combine the mean and standard deviations of multiple independent variables, you simply sum the means together and you sum the variances together. Since the standard deviation is the square root of the variance, what you actually do is you take the square root of the sum of the squares of the standard deviations. So:    
Means:  
18 + 12 + 10 = 40    
Standard deviations  
sqrt(2^2 + 1^2 + 5^2) = sqrt(4 + 1 + 25) = sqrt(30) = 5.477225575    
So, for Jen's entire commute, the mean is 40 minutes with a standard deviation of 5.5 minutes.
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An Adult ticket at an amusement park costs $24.95 and a child's ticket costs $15.95. A group of 10 people paid $186.50 to enter
leva [86]

Answer:

There were 3 adults

Step-by-step explanation:

Step 1: Derive the first expression

a+c=10...equation 1

where;

a=number of adults

c=number of children

And total number of people=10

Step 2: Derive the second expression;

Total cost of tickets=(price per child ticket×number of children)+(price per adult ticket×number of adults)

where;

Total cost of tickets=$186.50

price per child ticket=$15.95

price per adult ticket=$24.95

number of children=c

number of adults=a

replacing;

(15.95×c)+(24.95×a)=186.5

24.95 a+15.95 c=186.5....equation 2

Step 3: Combine equation 1 and 2 and solve simultaneously

24.95 a+15.95 c=186.5

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24.95(a+c=10)

(24.95 a-24.95 a)+(15.95 c-24.95 c)=186.5-(24.95×10)

-9 c=-63

c=-63/-9

c=7

replace the value for c in equation 1

a+c=10

a+7=10

a=10-7

a=3

There were 3 adults

6 0
2 years ago
Stephen says that the numbers 38 and 40 are relatively prime. explain why he is incorrect in making this statement
bonufazy [111]

When you say that two numbers are relatively prime, it means that both numbers do not have a common factor except 1. Stephen is incorrect because 38 and 40 are both multiples of 2.

I hope I answered your question. Thank you <span>J</span>

5 0
1 year ago
Read 2 more answers
Ashley recently opened a store that uses only natural ingredients. She wants to advertise her products by distributing bags of s
jasenka [17]

Answer:

  3 1/2 hours

Step-by-step explanation:

This is a problem in units conversion. We want to get from bags to hours by way of minutes per bag. One bag takes an effort of 2/3 person·minute, so we need to divide the total effort by the number of persons and convert minutes to hours.

  (1575 bags)×(2/3 person·min/bag)/(5 person)/(60 min/h)

  = (1575)(2/3)(1/5)(1/60) h = 3.5

It will take the 5 of them about 3 1/2 hours to prepare 1575 bags.

6 0
1 year ago
Read 2 more answers
The gas mileage for a certain vehicle can be approximated by m=−0.05x2+3.5x−49, where x is the speed of the vehicle in mph. Dete
Whitepunk [10]

Answer:

<h2>14mph</h2>

Step-by-step explanation:

Given the gas mileage for a certain vehicle modeled by the equation m=−0.05x²+3.5x−49 where x is the speed of the vehicle in mph. In order to determine the speed(s) at which the car gets 9 mpg, we will substitute the value of m = 9 into the modeled equation and calculate x as shown;

m = −0.05x²+3.5x−49

when m= 9

9 = −0.05x²+3.5x−49

−0.05x²+3.5x−49 = 9

0.05x²-3.5x+49 = -9

Multiplying through by 100

5x²+350x−4900 = 900

Dividing through by 5;

x²+70x−980 = 180

x²+70x−980 - 180 = 0

x²+70x−1160 = 0

Using the general formula to get x;

a = 1, b = 70, c = -1160

x = -70±√70²-4(1)(-1160)/2

x = -70±√4900+4640)/2

x = -70±(√4900+4640)/2

x = -70±√9540/2

x =  -70±97.7/2

x = -70+97.7/2

x = 27.7/2

x = 13.85mph

x ≈ 14 mph

Hence, the speed(s) at which the car gets 9 mpg to the nearest mph is 14mph

4 0
1 year ago
A rectangular prism has a volume of 170 cubic centimeters. The length of the prism is 5 centimeters, and the height of the prism
luda_lava [24]

Answer:

The width of the prism is 2 cm

Step-by-step explanation:

The given parameters are;

The volume of the prism = 170 cm³

The length of the prism = 5 cm

The height of the prism = 17 cm

The volume of the prism is given by the  relationship v = Length, l × Height, h × Width, w

Therefore;

The volume of the prism = 5 cm × 17 cm × w = 170 cm³

Which gives;

w = 170 cm³/(5 cm × 17 cm) = 170 cm³/(85 cm) = 2 cm

∴ The width of the prism = 2 cm.

7 0
1 year ago
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