Answer:
Step-by-step explanation:
First, we need to isolate 
by taking it common from both terms on the right:
Now, since we want in terms of the other variables, we can divide the left hand side (A) by whatever is multiplied with on the right hand side. Then we will have an expression for . Shown below:
This is the xpression for
There are 12 inches in a foot, so 9ft = 108in. Also, 80% = 0.8. Therefore the formula is:
h(n) = 108 * 0.8^n.
To find the bounce height after 10 bounces, substitute n=10 into the equation:
h(n) = 108 * 0.8^10 = 11.60in (2.d.p.).
Finally to find how many bounces happen before the height is less than one inch, substitute h(n) = 1, then rearrage with logarithms to solve for the power, x:
108 * 0.8^x = 1;
0.8^x = 1/108;
Ln(0.8^x) = ln(1/108);
xln(0.8) = ln(1\108);
x = ln(1/108) / ln(0.8) = -4.682 / -0.223 = 21 bounces
Answer:
15 = x
Step-by-step explanation:
Answer:
about 70 years
Step-by-step explanation:
Life expectancy (e) improves by 5.7 years every 10 years, so 5.7/10 = 0.57 years per year. For t years after 2009, it can be modeled by ...
e = 0.57t +80
We want to find when that is 120:
120 = 0.57t +80
40 = 0.57t
40/0.57 = t ≈ 70.2
About 70 years from 2009, humanity may achieve a life expectancy of 120 years.
