20 independent observations on a random variable X with unknown distribution function F(x) are:

142 134 98 119 131 103 154 122 93 137 86 119 161 144 158 165 81 117 128 103. find the 95% confidence interval for F(100).

my working:

i found that the sum of all 20 numbers are 2595. hence sample mean is 124.75.

after that what should i do?

thanks