A student fails to study for a 10-question true/false test. What is the probability that the student gets exactly 7 questions correct?
2007-05-31 10:06:12 · 5 answers · asked by Anonymous in Education & Reference ➔ Homework Help
Hi.
First think about the amount of possible combinations to give you 7 answers: this is 7 out of 10: or 10!/(7!*3!) = 120
But the total amount of possible (correct/incorrect) paths is 2^10 = 1024
The chance of getting exactly 7 right is: 120/1024
2007-05-31 10:44:26 · answer #1 · answered by ? 3 · 1⤊ 0⤋
The chances of the student getting any one question right is 1/2. The probability of getting two questions right is 1/2 * 1/2, or 1/4. Three is 1/8, etc. Seven correct is 1/(2^7) or 1/256
2007-05-31 17:16:54 · answer #2 · answered by Nick P 1 · 0⤊ 0⤋
The answer is 0.11718750000000029 (or 120/1024).
See below where
n=10 (number of questions)
k= 7 (stipulated number of correct answers)
p= 0.5 (probability of right answer)
Of course this is assuming the student is totally guessing, otherwise, p would be higher.
2007-05-31 18:09:12 · answer #3 · answered by Someone who cares 7 · 1⤊ 0⤋
i guess 7 out of 10
2007-05-31 17:11:37 · answer #4 · answered by Anonymous · 0⤊ 0⤋
1 in 1408.....better study.
2007-05-31 17:12:32 · answer #5 · answered by PC 2 · 0⤊ 0⤋