Her average in first three test = 89
This means, her total scores in first three test were = 3 x 89 = 267
Her average in four tests = 91
This means, her total scores in four tests are = 364
267 give the sum of first three test scores. and 364 give the sum of scores with fourth test adding in three tests.
So, subtracting 267 from 364 will give us the scores of Fourth test.
Scores of Fourth test = 364 - 267 = 97
Thus, Samantha's Claim is correct
0.56 < 0.65
or 0.56 is less than 0.65
You just divide the distance travelled by the time like so: 145mi/2.5h and get 58mph. You can convert the 145mi into meters and 2.5h into seconds (145mi is approximately 233345m; 2.5h is 9000 seconds) and get an approximate speed of 26m/s if you want to convert to SI units.
