A serial number is formed from the digits 1, 2, and 3, and the letters A and B.?

Question

Given that the serial number ends in a letter, what is the probability that it ends in 2A?

Answer 1

Chance that the last digit is an A 2:1
Chance that the 2nd to last digit is a 2 5:1

Total chance that last 2 digits are 2A 10:1

Answer 2

wow people need not answer if they dont know a thing about math. There are 48 different combinations you can make with 1,2,3,A,B with the last spot being a letter. Six of them end in 2a so the probabiltiy is 6:48 or 1:8.

123ab
132ab
312ab
321ab
231ab
213ab
123ba
132ba
231ba
213ba
321ba
312ba
12a3b
1a23b
2a13b
21a3b
a123b
a213b
a312b
a132b
1a32b
13a2b
31a2b
3a12b
32a1b
3a21b
23a1b
2a31b
a231b
a321b
12b3a
1b23a
2b13a
21b3a
b123a
b213a
b312a
b132a
1b32a
13b2a
31b2a
3b12a
32b1a
3b21a
23b1a
2b31a
b231a
b321a

to use a formula take the number of sports and multiply it out, but than you have subtract 3/5 of the answers because you only can use the result with letters(if that make sense) ..
1*2*3*4*5=120
3/5*120=72

120-72=48 so 48 possibilities

If you take out 2 and A there are 3 spots, (1*2*3) so that makes 6 combinations if the last two spots are 2 a.
so 6 out of 48 possibilities .

Answer 3

Let's try it this way...(I am not sure so it could be wrong).

You have five marles in a bag and they are each labled "1," "2," "3," "A," and "B"
I am going to pull one out but I ask myself...

"Self what is the probability I will pull one marble that is eithr a 2 or an A?"
Ans : there are 2 chances out of 5 that the one marble will be one or the other.

this means in order for this serial number to happen this pull has to be one or the other.
Also, for this serial number to happen we have to have the first one AND the second one. So this means, we multiply the results of each event.
It also means, once we pull one number we can contine to pull the other number, but we have to pull the first one in order to contine so that we have our serial number in the end. Each pull has to have one of the two digits for the serial number to happen.

Now we pull the second one, and now the odds are 1 out of 4 so we have

2/5 AND 1/4 =
2/5(1/4) = 2/20 = 1/10

So the probability of the serial number ending in 2A is 1/10 or .1

Answer 4

This is a conditional probability problem. You'll want to use this formula:

P(K|J)=P(K"and"J)/P(J)

The above statement reads: The probability of K given J is equal to the probability of K and J divided by the probability of J.

So in your case, your J (for this formula) is the event that the serial number ends in a letter. Your K is the event that the serial number ends in 2A.

So what you need to calculate now is the probability of the intersection of event K and J. The probability of event J alone should be easy. The intersection of K and J could be more difficult, you may need to use your text book to find some formulas or draw a tree.

Good luck.

Answer 5

25 to 1

Answer 6

5:1

Answer 7

There are 4^4 combinations that end in A, and 3^3 combinations that end in 2a, so the probability
P(xxx2A)|xxxxA) = 27/256 = 0.10546875

Answer 8

For the last symbol there are two possibilities (A, B).
For the second last symbol, five (A,B,1,2,3).

Therefore, the probability is 1:(2x5) = 1:10 or 10%.