In a bagm the ratio of the numbers of red, yellow and pruple balls are 4:3:5
Patrick puts n yellow balls in the bag. Then the probability of drawing a yellow ball become 1/3. Let the original number of yellow ball be m.
a.Prove that m=2n.
b. Find the least possible value of n
又係f.5 probability :(
2011-01-16 12:37 am
回答 (2)
2011-01-16 1:00 am
✔ 最佳答案
(a) Let the original number of yellow ball is m. Then the original numbers of red and pruple balls are 4m/3 and 5m/3 respectively.According to the information,
(m + n)/(m + n + 4m/3 + 5m/3) = 1/3
3(m + n) = m + n + 4m/3 + 5m/3
3m + 3n = 4m + n
m = 2n
(b) Since the values of 4m/3 and 5m/3 should be positive numbers. We conclude that m should be a multiple of 3. Also m is an even number. Let m = 6 then the least possible value of n is 3.
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