In this case, you need to calculate the future value and the formula to calculate that is:
FV=PV*(1+r)^n
FV=future value
PV=present value
r=rate
n=number of periods of time
The present value would be the price of the ring which is $1200. The rate is 5% per year and the number of periods of time is 30 years since you need to find the ring's worth in 30 years. Now, you can replace the values on the formula:
FV=1200*(1+0.05)^30
According to this, the answer is that the equation to calculate how much will it be worth in 30 years is: y = 1200(1+.05)^30.
Let p be the true proportion of US adults who believe raising the minimum wage will help the economy. A point estimate for p is and a good aproximation (because we have a large sample) for the standard deviation of is . Therefore, a 99% confidence interval for p is given by where and is the th quantile of the standard normal distribution, so we have, , i.e., or equivalently (0.3798, 0.4602).