Question 33547: Two distinct even numbers are selected at random from the first ten even numbers greater than zero. What is the probability that the sum is 30?
Answer by venugopalramana(3286)   (Show Source):
You can put this solution on YOUR website! Two distinct even numbers are selected at random from the first ten even numbers greater than zero. What is the probability that the sum is 30?
FIRST TEN EVEN NUMBERS >0 ARE
2,4,6,8,10,12,14,16,18,20....
SUM IS 30 IT IS GIVEN ..THAT IS EXACTLY EQUAL TO 30....SO
START WITH 2..PROCEED FROM LEFT TO RIGHT AND CHECK
WITH 2....NONE
WITH 4...NONE
WITH 6...NONE
WITH 8...NONE
WITH 10....1.....
WITH 12....1
WITH 14....1
WITH 16...NONE..SINCE IT IS ALREADY CONSIDERED UNDER 14
WITH 18...NONE..SINCE IT IS ALREADY CONSIDERED UNDER 12
WITH 20...NONE..SINCE IT IS ALREADY CONSIDERED UNDER 10
SO THERE ARE ONLY 3 COMBINATION POSSIBILITIES OUT OF 10C2 TOTAL COMBINATIONS
PROBABILITY = 3/10C2=3*8!*2!/(10!)=3*2/(10*9)=1/15
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