posted by .

Clara Nett is quite good and figures that her probability of playing any one note right is 99%. The solo has 60 notes.

a. What is her probability of each of the following?
1. Getting every note right.
My answer: 0.547

I am stuck on problems 2-5 because when I set up the nCx I got 0 for all the answers which is not sensable.....
2. Making exactly one mistake
3. Making exactly two mistakes
4. Making at least two mistakes
5. Making more than two mistakes
b. What must be Clara's probability of getting any one note right if she wants to have a 95% probability of getting all 60 notes right?
Is this the correct set up ?

My answer: 0.9991454771

  • Probability -

    #1 is correct, in effect what you are doing is

    C(60,60) (.99^60 (.01)^0 = .547

    #2, you want to have 59 correct and one wrong

    = C(60,59) (.99)^59 (.01)^1
    = 60(.55268..)(.01) = .33161

    #3 , same way, 58 correct, 2 wrong
    prob = C(60,58) (.99)^58 (.01)^2 = .09881

    #4 , at least 2 mistakes
    ---> making 2 mistakes + making 3 mistakes + .. + making 60 mistakes
    or 1 - making none - making 1

    = 1 - .547-.33161 = .12139

    #5 , making more than 2 mistakes
    ---> making 3 + making 4 + ... + making 60
    how does that differ from #4 ?

    b) to get a 95% we must have
    x^60 = .95
    take 60th root
    x = .95^(1/60) = .999145

    I think your problem is in evaluating something like

    by definition this is 60!/(58!2!)
    perhaps your calculator cannot carry those large numbers and overloads
    - most calculators have a function nCr
    on mine it is found along the "5" key and my keystrokes are:

    = to get 1770

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. stats

    if you randomly answer a t/f test and want to figure the possibililty of gettng at least an do you start and then once you have done this, what if you want to try it 4 more times?
  2. Intro to probability

    An octave contains twelve different musical notes (in Western music). How many different eight note melodies can be constructed from these twelve notes if: (a) no note can be used more than once?
  3. statistics

    The below table shows the probabilities generated by rolling one die 50 times and noting the up face. What is the probability of getting an odd up face?
  4. Math/Prob

    Claire takes a five-question true-false test. She hasn't studied, so she guesses at random. With her ESP she figures she has a 60% probability of getting any one answer wrong. A. What is the probability of getting an answer wrong?
  5. statistics - probability

    A total of 16 mice are sent down a maze, one by one. From previous experience, it is believed that the probability a mouse turns right is .38 a) What is the probability that 8 or fewer turn right?
  6. Statistics

    A total of 16 mice are sent down a maze, one by one. From previous experience, it is believed that the probability a mouse turns right is .38 a) What is the probability that exactly 8 of these 16 mice turn right?
  7. probability

    What is the probability of getting 80% or more of the questions correct on a 10-question true-false exam merely by guessing?
  8. statistics

    Suppose that each unit of a system is up with probability 2/3 and down with probability 1/3. Different units are independent. For each one of the systems shown below, calculate the probability that the whole system is up (that is, …
  9. Math

    Yalda has six $5 notes, ten $10 notes and four $20 notes in her purse. If she takes out one note, what is the probability that it will be: A) a $20 note B) a $5 or $10 note C) a $50 note D) she buys a new toaster with a $20 note and …

    1. The table shows the results of spinning a four-colored spinner 50 times. Find the experimental probability and express it as a decimal. P(not red) = ?

More Similar Questions