Question 1020321: A recent Wall Street Journal article indicated that 38% of American teenagers use Pandora's online radio service. Suppose a sample of 25 American teenagers are selected.
ALL ROUNDED TO 4 DECIMAL PLACES...
1.Find the probability that no less than 12 American teenagers use Pandora's online radio service. I got .2036
2.Find the probability that exactly 15 American teenagers do not use Pandora's online radio service. I got .1578
3.Find the probability that greater than 4 American teenagers use Pandora's online radio service. I got .9842
4.Find the probability that at least 17 American teenagers do not use Pandora's online radio service. I got .1390
5.Find the probability that no more than 6 American teenagers use Pandora's online radio service. I got .0606
Are these correct? I need to get them double checked, if it is wrong please work it out for me. Thank you.
Answer by Boreal(15235)   (Show Source):
You can put this solution on YOUR website! The table for 38% is not there, but the expected value is 9.5, so one would expect numbers to be near that.
Probability of 15 is 25C10(.38)^10(62)^15=01578 YOU ARE CORRECT
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GREATER THAN 4: FROM DOWN BELOW IT IS 0.0158 LESS, SO YOU ARE ALSO CORRECT
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At least 17 is 25C17*.62^17*.38^8=0.1390. This is exactly 17. There needs to be included the higher numbers
For 18, is 0.1008
For 19, is 0.0606
For 20 is 0.0297.
For 21 is 0.0115
For 22 is 0.0034
For 23 is 0.0007
For 24 is 0.0002
Answer is 0.3459
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no more than 6
probability of 6 is 0.0606.
of 5--- 0.0297
of 4---0.0115
of 3---0.0034
of 2---0.0007
of 1---0.0002
of 0--NS
That adds to 0.1061. The probability of 6 alone is 0.0606.
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Probability of 12--0.0943
Probability of 13--0.0578
Probability of 14--0.0304
Probability of 15--0.0136
Probability of 16--0.0052
Probability of 17--0.0011
Probability of 18--0.0005
Probability of 19--0.0001
12,13,14....,25.
That probability of no fewer than 12 is 0.2030. Rounding might explain our differences.
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