On pg 42 of BWG is states that skills require a number of challenging tests equal to one third the exponent (rounded up). This would mean that for exponents 1-3, one test is required. For exponents 4-6, two tests are required, and for exponents 7-9, three tests are required.
However, the chart on the same page says that for exponents 1-5, one test is required; for exponents 6-7, two tests are required; and for exponents 8-9, three tests are required.
Which is correct? The paragraph or the chart?