Conduct a two-sample test of means. A study by a bank compared the average savings of customers who were depositors for three years or less with those who had been depositors for more than three years.The results of a sample are < or equal mean balance savings 1,200, population standard deviation 100, and sample size 10. > 3 years mean savings balance 1,250, population standard deviation 150, and sample size 15. To test the two groups of customers have equal savings rates, what is the critical value of using a=0.05?