**4. Correct. The answer is false **

A type I error is made by rejecting a null hypothesis when is true.

We know that 't' calculated is:

(34.8 - 30)/16.7332 = 0.286855

And 't' from table for 60 degree of freedom is 1.671 (This value is for one tail because the alternative hypothesis is 'greater than').

Since 't'
calculated (t_{c}) is less than t from the
table (t_{t}) this value (t_{c})
lies in the region f acceptance the null hypothesis. Then we accept the null
hypothesis which states: b = 30 and we reject the null hypothesis we are
committing an error type I.

Therefore the probability of making type error I is a = 0.05 or 5%.