-I am so lost. I can't figure out whether to use permutaion or combination..I thought maybe combination since the order doesn't seem to matter..but I'm not getting 210 as the answer. Any ideas?

a hat contains tickets w/numbers 1,2...20 printed on them. if 4 tickets are drawn from the hat, without replacement, determine the probability that all are primes.

-well there are 8 primes. i did (8x7x6x5)/20P4 and got 14/969

i was wondering if that's correct

Any help will be appreciated thank you