Question

The online game World of Warcraft has seen a decline in subscribers in recent years. The number of subscribers peaked in 2010 at 11.99 million; in 2015, this number had declined to 5.43 million. Suppose this decline follows the exponential law, and continues uninhibited. If N is the number of subscribers, m millions, and t is the time, in years, since 2010, then:

1. Find a function N that describes this decline.
2. What will the number of subscribers be in 2019?
3. In what year will the number of subscribers fall below 1, 500,000?

Answer 1

Kindly check explanation

Explanation:

Given that:

Number of subscribers in 2010 = 11.99 million

Number of subscribers 2015 = 5.43 million

Let :

N = number of subscribers in millions

t = time in years

Exponential function which describes this decline :

N(t) = No×e^kt

Solve for k at t = 5

11,990,000 = 11,990,000 × e^k*0

5,430,000 = 11,990,000 × e^5k

0.4528773 = e^5k

In(0.4528773) = In(e^5k)

−0.792134 = 5k

k = −0.792134 / 5

k = −0.158426

What will the number of subscribers be in 2019?

In 2019

t = (2019 - 2010) = 9

N(t) = 11,990,000×e^(−0.158426*9)

= 11,990,000 * e^(−1.425841)

= 11,990,000 × 0.2403062

= 2,881,511.5 = 2,881,511

3. In what year will the number of subscribers fall below 1, 500,000?

N(t) = No×e^kt

1,500,000 = 11,990,000 × e^(−0.158426*t)

0.1251042 = e^(−0.158426*t)

In(0.1251042) = In(e^(−0.158426*t))

−2.078607 = 0.158426*t

t = (−2.078607 / 0.158426)

t = −13.12036

After 13.12036 years

2010 + 14 = 2024