Some researchers claim that herbal supplements such as ginseng or ginkgo biloba enhance human

Some researchers claim that herbal supplements such as ginseng or ginkgo biloba enhance human memory.  To test this claim, a researcher selects a sample of n = 25 college students.  Each student is given a ginkgo biloba supplement daily for six weeks and then all the participants are given a standardized memory test.  For the population, scores on the test are normally distributed with μ = 70 and σ = 15.  The sample of n = 25 students had a mean score of M = 75. 

Are the data sufficient to that the herb has a significant effect on memory?  Use a two-tailed test with α = .05.