A researcher thinks that people who drive red cars drive faster than people who drive silver cars. He recorded the speeds of a random sample of 42 red cars on a highway to find a mean of 70.17 mph and a variance of 10.18. He also recorded speeds of a random sample of 53 silver cars on a highway to find a mean of 69.02 mph and a variance of 8.84. Calculate the t-statistic for a test of the difference between the two sample means. (Report the value of t to 2 decimal places.)