Twenty weekend shoppers spend $78 on average and twenty weekday shoppers $67. Test whether mean spending differs and report the p-value.

A researcher samples 20 weekend and 20 weekday shoppers independently. Weekend shoppers spend $78 on average (sd $22); weekday shoppers $67 (sd $20). Assuming simple random sampling, equal variances and approximately normal spending, test whether mean spending differs and report the attained significance level (p-value).