Question 180539
1.) When text messaging on a telephone, pressing a 3 types D, E, F, or 3. Pressing a 7 types P, Q, R, S, or 7. How many messages are possible by pressing a 3, a 7, and then a 3? 
Ans: 3*4*3 = 36
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11.) What is the probability that a random 2-digit number is a multiple of 7?
Ans: There are 99 2-digit numbers if you do not include 00.
Multiples of 7 are: 7,14,21,28,35,42,49,etc, 98
So there are 14 multiples of 7 that are 2-digit numbers
Ans: Probability = 14/99
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13.) A mother is making different lunches for each of her 3 children. If each child grabs a lunch bag at random, what is the probability that all 3 children will get the correct bag? 
Ans: There are 3!=6 possible ways to pick the bags; only 1 is the right way.
Probability = 1/6
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21.) Two number cubes are rolled--one blue and one yellow. Find the probability that the yellow cube is even, and the sum is 7.
(yellow is even and sum is 7) = (2,5), (4,3), (6,1)-------3 elements
Total number of outcomes: 6*6 = 36
Probability(yellow even and sum is 7) = 3/36 = 1/12
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Explain why the events are dependent.
I'll leave that to you.
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Cheers,
Stan H.