First, add the frequencies in order to obtain the total number of surveyed people,
[tex]T=12+20+38+20+10=100[/tex]
Then, the condition 'a teenager has 4 or more pairs of shoes' is satisfied if the number of shoes is either 4 or 5; then,
[tex]P(4or5)=P(4)+P(5)=\frac{20}{100}+\frac{10}{100}=\frac{30}{100}=\frac{3}{10}[/tex]
The exact answer is 3/10 or 0.3 (both are equivalent)
