Can someone help me with this please

for 7
Yes it is right cuz 16 is the double of 8 and even the price if doubled up so the price is right
for 8
Apply the formula
[tex]2\sqrt{\frac{Area}{\pi } }[/tex]
[tex]2\sqrt{\frac{154}{\pi } }[/tex]
[tex]2\sqrt{49.02}[/tex]
[tex]2(7)[/tex]
[tex]14[/tex]
the diameter is 14
Hope this helps :)