**Question:**

**A mobile phone is put to use when the battery power is 100% . The
percent of battery power ‘y’ (in decimal) remaining after using the mobile
for x hours is assumed as = −0.25 + 1.
(i) Draw the graph of the equation.
(ii) Find the number of hours elapsed if the battery power is 40%.
(iii) How much time does it take so that the battery has no power**