Answer:
The best estimate for the proportion of ticket buyers that make purchases using their smart phones is 0.45.
Step-by-step explanation:
We take the estimate from the website, and expand for all buyers, to find the proportion that use their smartphones.
400 users of the website were randomly sampled from the existing database and 180 were found to have used their smart phones.
180/400 = 0.45
The best estimate for the proportion of ticket buyers that make purchases using their smart phones is 0.45.
X = number of cds on the rack
x + 7 = 30
x = 30 - 7
x = 23 <== so there are currently 23 cds on the rack
Invested at 3% = x
invested at 4% = 2x
invested at 5% = x+500
0.03x + 0.04(2x) + 0.05(x+500) = 2025
0.03x + 0.08x +0.05x +25 = 2025
0.16x = 2000
x= 12,500
4% = 2x = 12,500 * 2 = $25,000
3.8 is the answer you already figured it out