PSY 4501-A set of researchers measured mean number of item

1:

• A set of researchers measured mean number of item recognized in a visual recognition test comparing non-video game players and videogame players. They studied 12 non-games and 12 gamers. The non-gamers have a mean recognition of 3.25. The gamers have a mean recognition of 4.75. The pooled variance is 4.Calculate the t-statistic. SHOW YOUR WORK.
• Is the result is statistically significant?

2:

• The researchers tested performance on a task before and after training on a video-game task. 20 non-gamers participate in the study. There is a mean improvement of 24 ms. in reaction time on the task , with a variance of 18.Calculate the t-statistic. SHOW YOUR WORK.
• Is the result is statistically significant?

3:

• You are curious about whether video gamers are better at math than non-gamers. You find 8 of your friends, 4 gamers and 4 non-gamers, and give them SAT-style math questions. You count the number of correct responses and record the results below:

GamersNon Gamers

5 10

8 8

9 12

6 14

Mean = 7 Mean = 11

1. Calculate the t-statistic. SHOW YOUR WORK.
2. Is the result is statistically significant?