help with combinations and permutation (1 Viewer)

[vones]

can u help me solve this

7 letters are picked form the english alphabet.. find the probability that 3 of them will be vowel.

the average baby girl born per minute is 4.. whats the probability that in a particular minute there will be 2 baby girls

in a universtity.. 0.60 percent of the student pass the entrance exam. of the next 10 students. find the probability that exactly 4 of them will fail

 

[leisl1990]

5p3*21p4 over 26p7

i can only solve the first one.
those a hard questions..