Based on a random sample of size 50, you observe a sample mean of 143.6 and a sample standard deviation of 38.1. You then calculate a 95% confidence interval for the population mean, and it has length L1. Now suppose that the sample size had instead been 150, but with the same sample mean and the same sample standard deviation. Let L2 be the length of a 95% confidence interval for the population mean based on this larger sample. Which of the following is closest to the ratio L2/L1? a. 0.78
b. 0.57
c. 0.86
d. 0.65