The data shows the backpack weights for 7th and 8th graders. Is there a meaningful difference between the weights of the 7th grade backpacks and the weights of the 8th grade backpacks?

You can figure out if there is a meaningful difference between the weights of 7th grade backpacks and the weights of 8th grade backpacks by comparing the difference in their means to twice the larger MAD. Start by finding the difference in means.