52 3. Three different roads feed into a freeway entrance. Over an hour's time, the number of cars entering the freeway for each road is a RV with expected value and standard deviation given by 194 Road 1 Road 2 Road 3 180 Expected value Standard deviation 36 900 500 22 15 a) What is the expected number of cars entering the freeway over an hour? b) What is the standard deviation of the number of cars entering the freeway?

MATLAB: An Introduction with Applications
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Author:Amos Gilat
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Chapter1: Starting With Matlab
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**Problem Statement:**

Three different roads feed into a freeway entrance. Over an hour’s time, the number of cars entering the freeway for each road is a random variable (RV) with the expected value and standard deviation provided below:

| Road   | Expected Value | Standard Deviation |
|--------|----------------|--------------------|
| Road 1 | 180            | 36                 |
| Road 2 | 900            | 22                 |
| Road 3 | 500            | 15                 |

**Questions:**

a) What is the expected number of cars entering the freeway over an hour?

b) What is the standard deviation of the number of cars entering the freeway?

**Solution:**

a) The expected number of cars is the sum of the expected values from all roads:

\[
\text{Expected number of cars} = 180 + 900 + 500 = 1580
\]

b) The standard deviation of the total number of cars is calculated using the formula for the sum of independent random variables:

\[
\text{Standard deviation} = \sqrt{36^2 + 22^2 + 15^2} = \sqrt{1296 + 484 + 225} = \sqrt{2005} \approx 44.8
\]

An additional calculation shows a total variance of approximately 33,780 (shown in the work as a verification step).
Transcribed Image Text:**Problem Statement:** Three different roads feed into a freeway entrance. Over an hour’s time, the number of cars entering the freeway for each road is a random variable (RV) with the expected value and standard deviation provided below: | Road | Expected Value | Standard Deviation | |--------|----------------|--------------------| | Road 1 | 180 | 36 | | Road 2 | 900 | 22 | | Road 3 | 500 | 15 | **Questions:** a) What is the expected number of cars entering the freeway over an hour? b) What is the standard deviation of the number of cars entering the freeway? **Solution:** a) The expected number of cars is the sum of the expected values from all roads: \[ \text{Expected number of cars} = 180 + 900 + 500 = 1580 \] b) The standard deviation of the total number of cars is calculated using the formula for the sum of independent random variables: \[ \text{Standard deviation} = \sqrt{36^2 + 22^2 + 15^2} = \sqrt{1296 + 484 + 225} = \sqrt{2005} \approx 44.8 \] An additional calculation shows a total variance of approximately 33,780 (shown in the work as a verification step).
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