Answer:
about 15 hours
Step-by-step explanation:
You want to find t such that N(t)=200. Fill in the equation with that information and solve for t.
200 = 400/(1 +399e^(-0.4t))
1 +399e^(-0.4t) = 400/200 = 2 . . . . . multiply by (1+399e^(-0.4t))/200
399e^(-0.4t) = 1 . . . . . . . . . . . . . . . . . . subtract 1
e^(-0.4t) = 1/399 . . . . . . . . . . . . . . . . . .divide by 399
-0.4t = ln(1/399) . . . . . . . take the natural log
t = ln(399)/0.4 ≈ 14.972 . . . . . . . divide by -0.4, simplify
Rounded to tenths, it will take 15.0 hours for half the people to have heard the rumor.
10 is the old value and 3 is the new value. In this case we have a negative change (decrease) of -70 percent because the new value is greater than the old value. The answer is -70 percent.
Answer:
18 and 9
Step-by-step explanation:
The numbers are x and 1/2x.
x + 1/2x = 27
3/2x = 27
x = 18 so the numbers of 18 and 9.
Simplify 10^4 to 10000
8.5x10000-3.0x10^3
Simplify 8.5x*10000 to 85000x
85000x-3.0*10^3
Simplify 3.0x10^3 to 3*10^3
Answer 85000x-3*10^3