The number of cell phones in the united states was 1.2 million in 1995. if the annual increase in the number of phone per year is 21%. in what year will there be 1 billion cell phones in use

Year 2031

Step-by-step explanation:

We need to use the formula for compound growth here, that is:

Where

F is future amount (1 billion)

P is present amount (1.2 million)

r is rate of growth (21% or 0.21)

t is the time (we need to find this)

Putting in the values we have:

So after about 35.28 years, the number of phones will cross 1 billion, so we take the next year, so after 36 years.

From 1995 to 36 years would be the year 2031

can you add an image ?

step-by-step explanation:

distance covered by pamela in 9 l of fuel = 99km

let us apply unitary method here.

distance covered by pamela in 1 l of fuel =99/9 =11 km

now let us find distance covered by pamela if she has 12 l of fuel.

distance covered in 12 l = distance covered in 1 l of fuel * 12

we know that distance covered by here in 1 l is 11 km.

so distance covered in 12 l of fuel = 11*12 = 132 km.