Compute the Variance and Standard Deviation of a Discrete Random

question 22

Multiple Choice

Compute the Variance and Standard Deviation of a Discrete Random Variable
-A manager at a local company asked his employees how many times they had given blood in the last year. The results of the survey are given below. The random variable x represents the number of times a person gave blood and P(x) represents the probability of selecting an employee who had given blood that percent of the time. What is the standard deviation for the number of times a person gave blood based on this survey $\begin{array}{|c|c|c|c|c|c|c|c|}\hline x & 0 & 1 & 2 & 3 & 4 & 5 & 6 \\\hline P(x) & 0.30 & 0.25 & 0.20 & 0.12 & 0.07 & 0.04 & 0.02 \\\hline\end{array}$

• A) \(1.54\)
• B) \(1.82\)
• C) \(1.16\)
• D) \(2.23\)

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Definitions:

Circuit

In electricity, a path for electrons to flow from a source of higher electrical potential to a source of lower potential.

Timing Belt

A belt that synchronizes the rotation of the engine's crankshaft and camshaft, ensuring that the valves open and close at correct intervals.

Relative Compression Test

A quick way to identify a weak cylinder by cranking the engine with an inductive ammeter on the starter circuit. With a lab scope, cranking amperage can be graphed and correlated to a particular cylinder. A cylinder with low compression will draw fewer amps than a cylinder with higher compression, which will show on the graph.

Inductive Ammeter

An instrument used for measuring electrical current without the need to make direct contact with the conductor.