You need 10 right to pass. what s the likelihood if you guess at every questions, you will pass? What is the number of questions you can expect to get correct?
2006-11-21 05:24:53 · 5 answers · asked by Kelly D 1 in Science & Mathematics ➔ Mathematics
Number of questions you expect to get correct = 20/4 = 5
Odds of getting a question wrong = 3/4
Odds of getting a question right = 1/4
Different ways of getting R questions right = 20 C R
Odds of getting R questions right = 20CR * (1/4)^R * (3/4)^(20-R)
Odds of passing = 1 - odds of getting less than 10
Odds of getting 0-9 right (using excel)
= POWER(1/4, X) * POWER(3/4, 20-X) *FACT(20)/FACT(X)/FACT(20-X)
0.003171212
0.021141413
0.066947808
0.133895615
0.189685455
0.202331152
0.168609293
0.112406195
0.060886689
0.027060751
= 0.986135583 chance of failing
Chance of passing = 1 - 0.986135583
= 0.013864
Not very high.
2006-11-21 05:51:37 · answer #1 · answered by Leltos 5 · 0⤊ 0⤋
When you guess on a problem that has four choises you have a 1 to 4 chance. So you could get 5 questions right, if you guessed all of em.
2006-11-21 05:28:33 · answer #2 · answered by Jenna-Kate 2 · 0⤊ 0⤋
probability of getiing it right = 1/4
so you would expect to get 5 right
likelyhood of getting ten right is 1/2 the likely hood of getting 5 right
=(1/4)/2
= 1/8
hope this helps
2006-11-21 05:28:15 · answer #3 · answered by billymardle 1 · 0⤊ 0⤋
Probability, huh?
2006-11-21 05:28:16 · answer #4 · answered by Smiles 4 · 0⤊ 0⤋
dont know
2006-11-21 05:26:32 · answer #5 · answered by babygirl 1 · 0⤊ 0⤋