Answer:
40%
Step-by-step explanation:
Percentage Error
[tex] =\frac{change-in-time}{ exact- time} \times 100\%[/tex]
From the question,
the approximated time=30 minutes.
Change in time= approximated time minus exact time = 42-30=12 minutes
This implies:
[tex] = \frac{12}{30} \times 100\%[/tex]
[tex] \frac{1200}{30}\%[/tex]
[tex]=40\%[/tex]
Hence Mr. Rowan's percent error
is 40%