i need help on a lab

here are the results
Mass of empty beaker and glass rod(62.62)
Mass of beaker, glass rod, hydrated copper sulfate(66.02)
Mass of beaker, glass rod and anhydrous copper sulfate(65.04)
Mass of hydrated copper sulfate(3.4)
Mass of anhydrous copper sulfate(2.42)
Mass of water (0.98)

Determine the percent by mass of water in your sample of hydrated copper(II) sulfate.

my work
0.98/3.4 x 100% = 28.8%
is that right

That calculation looks ok to me.

To determine the percent by mass of water in the sample of hydrated copper(II) sulfate, you used the correct formula:

Percent by mass = (mass of water / mass of hydrated copper sulfate) x 100%

Substituting the values you provided:
Percent by mass = (0.98 g / 3.4 g) x 100% = 28.8%

So, your answer of 28.8% is correct. Well done!