n=10, x=4, p=.5

If your binomial probability tables are cumulative, which most are, then you
will have to

1. look up the probability with n=10, x=4, p=.5 and find .3770 which is the
probability that you will get 4 or 3 or 2 or 1 or 0 heads,

 and then

2. look up the probability with n=10, x=3, p=.5 and find .1719 which is the
orobability that you will get 3 or 2 or 1 or 0 heads,

and then

3. subtract the result from 2 from the result of 1. .3770 - .1719
 and get .2051

[If your binomial table is not cumulative you will read it directly as
 .2051 with n=10, x=4, p=.5]
 
Edwin