Question

what is the probability of getting a head when tossing 4 coins simultaneously

Answer 1

just one head? Means one head, three tails.

Pr= .5^4

Answer 2

I read that as a binomial distribution.
so
C(4,1) (1/2)^1 (1/2)^3
= 4(1/2)^4
= 1/4

or

there are 2^4 or 16 cases
your event could be
HTTT
THTT
TTHT
TTTH, or 4 possibilities
prob(exactly one head) = 4/16 = 1/4

Answer 3

I agree on 1/4, the answer I posted is of getting a HTTT, but there are four ways of getting a H (first, second, third, ..), or Pr=4/16 or 1/4

Thanks for checking Reiny.