When x is decreased by 2, and then that number is divided by 2, the result is 2. What is the value of x?

The population of rabbits on an island is growing exponentially. In the year 1991, the population of rabbits was 9100, and by 19

lisabon 2012 [21]

Answer:

$39,223\ rabbits$

Step-by-step explanation:

we know that

The equation of a exponential growth function is given by

$y=a(1+r)^x$

where

y is the population of rabbits

x is the number of years since 1991

a is the initial value

r is the rate of change

we have

$a=9,100$

substitute

$y=9,100(1+r)^x$

For the year 1998

the number of years is equal to

x=1998-1991=7 years

so

we have the ordered pair (7,18,000)

substitute in the exponential equation and solve for r

$18,000=9,100(1+r)^7$

$(18,000/9,100)=(1+r)^7$

elevated both sides to 1/7

$(1+r)=1.1023$

$r=0.1023$

therefore

$y=9,100(1+0.1023)^x$

$y=9,100(1.1023)^x$

Predict the population of rabbits in the year 2006

Find the value of x

x=2006-1991=15 years

substitute the value of x in the equation

$y=9,100(1.1023)^{15}$

$y=39,223\ rabbits$

6 0

2 years ago

Briony invests some money. Interest is paid on the money at a rate of 2% per annum for the first year and 1% per annum for the s

nalin [4]

Answer:

Brionny invested £8400.

Step-by-step explanation:

Simple Interest

This is a simple interest problem.

The simple interest formula is given by:

$E = P*I*t$

In which E is the amount of interest earned, P is the principal(the initial amount of money), I is the interest rate(yearly, as a decimal) and t is the time.

After t years, the total amount of money is:

$T = E + P$

In this question:

We divide in two intervals, the first year and the second year. We have to know that the amount after the end of the first year is the principal at the start of the second year.

First year:

Amount of 2% interest, during 1 year.

So the interest earned is:

$E = P*I*t = P*0.02*1 = 0.02P$