Conditional Probability and Independence: Practice Now Basics 2

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Practice Material for 'The Basics' 2

This table reports the number of alcohol-related fatal crashes by time of day, using 1995 US Motor Vehicle Crash data:

Fatal Crashes by time	Alcohol Related	Total
3-6 pm	1,679	6,242
6-9 pm	2,826	5,923
9 pm - midnight	3,500	5,441
Midnight -3 am	3,698	4,757
All Fatal Crashes	15,386	37,221

a. Find the probability that a fatal crash is alcohol related.
(Stan )Radio: a. 0.269 b. 0.777 c. 0.413

Possible answer

b. Find the conditional probability that a fatal crash is alcohol related for the midnight to 3 am time period.
(Stan )Radio: a. 0.269 b. 0.777 c. 0.413

Possible answer

c. Are the proportion of alcohol related fatal crashes and time of day independent or dependent events?
(Stan )Radio: a. Can't tell b. Independent c. Dependent

Possible answer