A container of 20ft carry a weight that is normally distributed with a mean of 5000 t and a standard deviation of 400 t. What percentage of container weight between 5400 and 5600 t?

This is where I reached, how should I conclude on the percentage?

For χ = 5400

Z_{5400}= (5400-5000)/400

Z_{5400}= 10

For χ = 5600

Z_{5600}= (5600-5000)/40

Z_{5600}= 15