Question

4. A typical smartphone battery (yes that includes iphones) degrades at approximately 1%

battery capacity per month with typical use.
a. Construct an equation using f(t) and t that represents the relationship between
"f(t)" the battery capacity of a typical smartphone after "t" months and "L" the
number of months the smartphone has been in normal use.
b. What does the horizontal intercept represent in context? (The x-intercept)
c. What does the vertical intercept represent in context? (The y-intercept)

Answer 1

a.
`f(t) = (0.99)^(t) 100%\\`

b. The x - intercept represents the time at which the battery life drops to 0 %.

c. The y - intercept represents the initial battery life.

Explanation:

a. Construct an equation using f(t) and t that represents the relationship between

"f(t)" the battery capacity of a typical smartphone after "t" months and "L" the

number of months the smartphone has been in normal use.

Let the initial battery life be I.

After one month, it decreases by 1%. So, our new value, I' = initial value - decrease = I - 1%I = 99%I.

After two months, it decreases by 1% to our new value I". So, our new value, I" = initial value - decrease = I' - 1%I' = 99%I' = 99%(99%)I = (99%)²I

After three months, it decreases by 1% to our new value I'". So, our new value, I"' = initial value - decrease = I" - 1%I" = 99%I" = 99%(99%)²I = (99%)³I

We see a pattern here.

After t months, f(t)

`f(t) = (0.99)^(t) 100%\\`

b. What does the horizontal intercept represent in context? (The x-intercept)

The x - intercept represents the time at which the battery life drops to 0 %.

c. What does the vertical intercept represent in context? (The y-intercept)

The y - intercept represents the initial battery life.