Two separate samples are being employed to determine the population mean difference between two treatment conditions. Which of the following would produce the widest confidence interval?
1. n1 = n2 = 10 with a pooled variance of 100
2. n1 = n2 = 10 with a pooled variance of 10
3. n1 = n2 = 20 with a pooled variance of 100
4. n1 = n2 = 20 with a pooled variance of 10