1.A weight-lifting coach claims that weight-lifters can increase their strength by taking a certain supplement. To test the theory, the coach randomly selects 12 athletes and gives them a strength test using a bench press. Thirty days later, after using the supplement with regular training, , the same 12 athletes are tested again. Test the claim that the supplement does increase the athletes' strength. Use = 0.05. Assume that the distribution is normally distributed.

Note: Strength is measured in amount of weight in kilograms an athlete can lift.