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Papessa [141]
2 years ago
8

Lamar and lawrence run a two-person lawn-care service. they have been caring for mr. johnson's very large lawn for several years

, and they have found that the time it takes lamar to mow the lawn itself is approximately normally distributed with a mean of 105 minutes and a standard deviation of 10 minutes. meanwhile, the time it takes for lawrence to use the edger and string trimmer to attend to details is also normally distributed with a mean of 98 minutes and a standard deviation of 15 minutes. they prefer to finish their jobs within 5 minutes of each other. what is the probability that this happens, assuming their finish times are independent?

Mathematics
2 answers:
Serggg [28]2 years ago
4 0

Answer:

0.2892

Step-by-step explanation:

Let X be the time for Lamar to finish and Y for Lawrence

Given that X is N(105, 10)

Y N(98,15)

consider the random variable x-y

Since x and y are independent we have

x-y is normal with mean = 105-98 =7

and variance of x-y = varx +vary

= 100+225 =325

STd dev = sq rt 325 =18.03

X-Y = U is N(7, 18.03)

Required probability

= P(|x-y|<5)=P(-5<U<5)

Convert to std normal variate Z

-5 becomes (-5-7)/18.03 =-0.67

5 becomes  (5-7)/18.03 =-0.11

Hence required prob

P(-0.67<Z<0.11) = 0.2454+0.0438

=0.2892

Naddik [55]2 years ago
3 0
The difference of finish times has a mean of
  μ = 105 -98 = 7 . . . . minutes
and a variance of
  σ² = 10² +15² = 325 . . . . minutes²

Using a probability calculator, we find the probability to be
  p(-5 < x < 5) ≈ 0.2030

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Answer:

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Step-by-step explanation:

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2 years ago
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Solution:

we are given that

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Answer:

x=30\\y=68\\z=82

Step-by-step explanation:

x = measure of the first angle

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y+z=5x

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x+y+z=180

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y+z=5x\\z=y+14\\x+y+z=180

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x+y+z=180\\x+(y+z)=180\\x+(5x)=180

Distribute the + sign

x+5x=180

Combine like terms;

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Divide by 6.

x=\frac{180}{6}\\ x=30

We have now defined that the measure of the first angle is 30º.

Let's take another equation... for example z=y+14

I'm going to take this one because if I replace x and z in the third equation, all I'll have left will be y.

x+y+z=180\\30+y+(y+14)=180

Distribute the + sign and Combine like terms;

30+y+y+14=180\\44+2y=180\\

Subtract 44 to isolate 2y.

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Step-by-step explanation:

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Step 2:

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7 0
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