A decision maker is interested in estimating the mean of a population based on a random sample. She wants the confidence level to be 90% and the margin of error to be 0.30. She does not know what the population standard deviation is, so she has selected the following pilot sample:

8.80 4.89 10.98 15.11 14.79 16.93 1.27 9.06 14.38 5.65 7.24 3.24 2.61 6.09 6.91 Based on this pilot sample, how many more items must be sampled so that the decision maker can make the desired confidence interval estimate?