Answer: [tex]171.4\%[/tex]
Step-by-step explanation:
Given
Time is extended from 28 days to 76 days
The percentage increase is given by
[tex]\Rightarrow \dfrac{\text{New-original value}}{\text{original value}}\times 100[/tex]
Putting values
[tex]\Rightarrow \dfrac{76-28}{28}\times 100=\dfrac{48}{28}\times 100\\\\\Rightarrow 171.4\%[/tex]
Thus, the percentage increase in time is [tex]171.4\%[/tex]