Please answer this question.

Mass of Helium = 4
Helium = 55 liters
How many moles = ?
By the equation(AT S.T.P) of,
Moles = [tex]\frac{Given\ Volume}{22.4\ dm^3}[/tex]
Substitute the values,
Moles = [tex]\frac{55}{22.4}[/tex]
Simplify the fraction,
Moles = 2.5 grams/moles