Answer:
6.75 hours.
Step-by-step explanation:
Given:
Time lasted on full charge = 9 hours.
CD's charged by Amy = [tex]\frac{9}{12}[/tex] of full charge.
Using unitary method, we solve for the time the CD's will last for given charge.
This can be done by multiplying the time for 1 complete charge and the fraction of the charge done.
∵ Time required for 1 complete charge = 9 hours.
∴ Time required for [tex]\frac{9}{12}[/tex] of full charge = [tex]\frac{9}{12}\times 9[/tex]
⇒ Time required for [tex]\frac{9}{12}[/tex] of full charge = [tex]\frac{81}{12}=6.75\ h[/tex]
Therefore, the time it will last for [tex]\frac{9}{12}[/tex] of full charge is 6.75 hours.
