Number of times Caroline served over the net = 16 times
Number of times Caroline did not serve over the net = 20 - 16 = 4 times
Hence, Percentage of her incorrect serves is given by:
[tex]\% = \frac{no \: of \: incorrect \: serves}{total \: no \: of \: serves} \times 100[/tex]
[tex]\% = \frac{4}{20} \times 100 \\ \\ \% = 20\%[/tex]
Caroline did not make 20% of her serves
