$1$ point$($s$)$

possible

Wake County has a special emergency rescue team. The team is practicing rescuing dummies from a smokefilled building. The first time, the team took $840$ seconds $(14$ minutes$).$ The second time, it took $672$ seconds $(11\mathrm{.}2$ minutes$).$

Click the icon to view the learning curves table.

a$.$ The estimated learning rate is $\%.($Enter your response as a whole number.$)$

b$.$ Suppose that the team's learning rate for the rescue exercise is $75\%.$

The team needs to repeat the exercise $$ times until its time is less than $249\mathrm{.}48$ seconds. $($Enter your response as a whole number.$)$

c$.$ It takes $$ seconds to perform the $20$th rescue if the learning rate is $75\%.($Enter your response rounded to one decimal place.$)$