1. In the Math/Physics building, 76% of classrooms have chalkboards and the othe
ID: 3128448 • Letter: 1
Question
1. In the Math/Physics building, 76% of classrooms have chalkboards and the other 24% have whiteboards. Of the classes taught in rooms with chalkboards, 65% are math courses, 15% are physics courses, and the remaining 20% are statistics courses. Of the classes taught in rooms with white boards, 15% are math courses, 38% are physics courses, and 47% are statistics courses. What percent of classes in the building are physics? What percent of physics classes are taught in white board rooms?
2. Oranges and apples are in a bag. 31% of the fruit has already gone bad. 56% of the fruit in the bag are oranges. 30% of apples have turned bad. If you pull out a piece of fruit that has gone bad, what is the probability it is an orange?
3. It is estimated that 81% of homes have working smoke detectors. On average, 22% of fires result in fatalities, but the presence of a working smoke detector cuts the risk to just 9%. If a random fire resulted in a fatality, what is the probability that the house had a working smoke detector? In homes without a working smoke detector, what is the risk of fatalities?
Explanation / Answer
2) LETS ASSUME WE HAVE TOTAL 100 APPLES
OUT OF WHICH AS GIVEN 31% = 31 FRUITS GOT BAD
TOTAL 56% =56 FRUITS ARE ORANGES
44%= 44 FRUITS ARE APPLES
30% OF APPLE ARE BAD = 30% OF 44 = 13
TOTAL ORANGES ARE BAD = 31- 13 = 18
THEREFORE IF WE PULL OUT BAD FRUIT
PROBABILITY OF IT BEING ORANGE = 18/31 = 0.580
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