a 98% confidence interval based on 24 observations is 50.0 to 55.4. what is the MOE?

Here's what i did:

I drew the graph with the confidence interval.

MOE= Z sub(alpha/2) X sigma/sqrt(n)
MOE= Z0.01 X sigma/sqrt(24)
MOE=2.33 X sigma/sqrt(24)

How do i find sigma?