Answer:
609
Step-by-step explanation:
Standard deviation = 
= $30
Margin of error = E = $2
Confidence level = 90%
Since the distribution is said to be normal, we will use z scores to solve this problem.
The z score for 90% confidence level = z = 1.645
Sample size= n = ?
The formula to calculate the margin of error is:
Using the values in above equation, we get:
This means, the minimum number of observations required is 609
Answer:
41.8 years
Step-by-step explanation:
From
A= 39000
r = 10.5%
P = $ 485
n=12
t = the unknown
t= [ ln(A) - ln(P) ] / n[ln(1 + r/n)]
t= ln 39000 - ln 485/ 12[ln(1+0.105/12)]
t= 10.57 - 6.18/0.105
t= 41.8 years
We can either convert to standard form first or convert to a common multiplier, kinda like a common denominator. The latter makes more sense if they wanted the result in scientific notation, but let's do it that way anyway.
a)
4.5 × 10⁴ + 3.8 × 10³ = 45 × 10³ + 3.8 × 10³ = 48.8× 10³ = 48,800
Answer: 48,800
b)
4.5 × 10⁴ - 3.8 × 10³ = 45 × 10³ - 3.8 × 10³ = 41.2× 10³ = 41,200
Answer: 41,200
c)
7.2 × 10⁻³ + 6.3 × 10⁻² = 7.2 × 10⁻³ + 63 × 10⁻³ = 70.2 × 10⁻³
= 7.02 × 10⁻² = 0.0702
Answer: 0.0702
