Question

Please help me solve this im not really sure how:( I’ve been trying no luck

Answer 1

Given the average score model;

`f(t)=85-6\log_(10)(t+1)`

On the original exam;

`\begin{gathered} t=0 \\ \\ f(0)=85-6\log_(10)1 \\ \\ f(0)=85 \end{gathered}`

His average score on the original exam is 85

(b) After one year;

`\begin{gathered} t=12 \\ \\ f(12)=85-6\log_(10)(12+1) \\ \\ f(12)=78.3 \\ \\ f(12)\approx78 \end{gathered}`

His average score after one year is 78

(c)

`\begin{gathered} f(t)=80 \\ \\ 80=85-6\log_(10)(t+1) \\ \\ (-5)/(-6)=\log_(10)(t+1) \\ \\ t+1=10^{((5)/(6))} \\ \\ t=6.81-1 \\ \\ t=5.81 \end{gathered}`