Can you help me with this question

Answer:
2.4 cm
Step-by-step explanation:
Formula
[tex]V = \pi r^{2} h[/tex]
Substitute Known Variables
[tex]138 = (3.14)(r^{2})(7.8)[/tex]
Multiply Known Variables
[tex]138 = (24.292)(r^{2} )[/tex]
Divide Volume By 24.292
[tex]\frac{138}{24.292} = r^{2}[/tex]
[tex]5\frac{4135}{6073} = r^{2}[/tex]
Find The Squared Root Of Both Numbers
[tex]\sqrt{5\frac{4135}{6073} } = \sqrt{r^{2} }[/tex]
[tex]2.38346021471... = r\\r = 2.38346021471...[/tex]
Round The Answer To The Nearest Tenth
2.4 cm