Explain, stating clearly the assumptions involved in the t-test for testing the significance of difference between two sample means. Measurements of the left-and-right-hand gripping strengths of 8 left-handed writers are recorded:

Person	1	2	3	4	5	6	7	8
Left hand	112	131	142	90	125	130	95	90
Right hand	104	136	135	86	132	120	86	85

Do the data provide strong evidence that the people who write with left hand have greater gripping strength in the left hand than they do in the right hand? Use α=0.05.