SOLUTION: Please you help me solve these problems. How do you know? Can you write everything that you solve its? 6.) What is the probability that a random 2-digit number (00-99) does not

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Question 179690This question is from textbook Theoretical and Experimental Probability
: Please you help me solve these problems.
How do you know?
Can you write everything that you solve its?
6.) What is the probability that a random 2-digit number (00-99) does not end in 5?
8.) A clerk has 4 different letters that need to go in 4 different envelopes. What is the probability that all 4 letters are placed in the correct envelopes?
Please answer me as soon as you could, Thank you. This question is from textbook Theoretical and Experimental Probability

Answer by stanbon(75887) (Show Source):
You can put this solution on YOUR website!
6.) What is the probability that a random 2-digit number (00-99) does not end in 5?
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There are 100 numbers if you include 00.
# that do not end in 5?
10 ways to pick the tens digit
9 ways to pick the ones digit
So, 10*9 = 90 ways to have a two-digit number not ending in 5
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Therefore P(2-digit not ending in 5) = 90/100 = 9/10
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8.) A clerk has 4 different letters that need to go in 4 different envelopes. What is the probability that all 4 letters are placed in the correct envelopes?
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# of possible arrangements: 4! = 24
# of correct arrangements: 1
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Probability of getting the right arrangement: 1/24
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Cheers,
Stan H.