Answer: She started with $160.
It will take 6 weeks before she has less than half of what she originally invested.
Step-by-step explanation:
If her money is decreasing in value by 11% each week, it means that the rate at which it is decreasing is exponential.
We would apply the formula for exponential decay which is expressed as
A = P(1 - r)^t
Where
A represents the value of the investment after t weeks.
t represents the number of weeks.
P represents the initial value of the investment.
r represents rate of depreciation.
From the information given,
A = $142.40
r = 11% = 11/100 = 0.11
t = 1
Therefore
142.40 = P(1 - 0.11)^1
142.40 = P(0.89)
P = 142.4/0.89
P = 160
For her to have half of what she invested originally, then
80 = 160(0.89)^t
80/160 = (0.89)^t
0.5 = (0.89)^t
Taking log of both sides to base 10
Log 0.5 = log0.89^t = tlog0.89
- 0.3010 = - 0.051t
t = - 0.3010/- 0.051
t = 5.9
Approximately 6 weeks
Answer:
x-y=-2
Step-by-step explanation:
Divide both sides if the equations by 3.
(3y-3x)÷3=6÷3
y-3x÷3=2
calculate the quotient
y-x=2
multiply both sides of the equation bub -1
-1x(-x)-1y=-1x2
any expression multiplied by -1
x-1y=-1x2
any expression multiplied by 1 remains the same.
x--y=-1x2
x-y=-2
Answer:
k = 10
Step-by-step explanation:
Difference means subtract.
2k - 8 = 12
is how that statement is translated.
Add 8 to both sides.
2k - 8 + 8 = 12 + 8
2k = 20
Divide by 2
2k/2 = 20/2
k = 10
Answer:
See below
Step-by-step explanation:
What we can do is try it out.
20*0.6=12
since 0.6 is left
now we increase 12 by 40, or multiply it by 1.4
12*1.4= 16.8
See what is happening here is that at first when we are decreasing it by 40 percent, we are taking 40 percent of 20. However, when we increase that amount by 40 percent, we are now increasing 40 percent of 20 by 40 percent, or increasing 16 by 40 percent. Therefore, we will not get the original amount.
Answer:
4
Step-by-step explanation:
You have positive number and it is bigger that negative so your result will be positive too:
7-3=4
