... there are gender-associated differences in mathematical ability (as is often claimed!) Take α = 0.05 Boys: 80 96 98 87 75 83 70 92 97 82 Girls: 82 90 84 70 80 97 76 90 88 86 (Hint: Group the grades ... testing H against A, consider the following sequential procedure: As long as a < λn < b, take another observation, and as soon as λn ≤ a, stop sampling and accept H and as soon as λn ≥ b, stop sampling ... cannot be repeated at will, in many other cases this is, indeed, the case In the latter case, as a rule, it is advantageous not to fix the sample size in advance, but to keep sampling and terminate...