A horticulturist working for a large plant nursery is conducting experiments on the growth rate of a new shrub. Based on previous research, the horticulturist feels the average weekly growth rate of the new shrub is 4cm per week. A random sample of 40 shrubs has an average growth of 1.50cm per week with a standard deviation of 5cm. Is there overwhelming evidence to support the claim that the growth rate of the new shrub is less than 4cm per week at a 0.200 significance level? Find the value of the test statistic. Round your answer to three decimal places, if necessary.