A horticulturalist wishes to test if runner beans produced by one variety (variety 'A') are less affected by pests and diseases than runner beans produced by another variety (variety 'B'). In particular the horticulturalist wishes to test the hypotheses

H₀: _A = _B and H₁: _A < _B

where _A is the population mean percentage of runner bean plants of variety A that are affected by pests and diseases and _B is the population mean percentage of runner bean plants of variety B that are affected by pests and diseases.

The horticulturalist gathers reports from gardeners on the percentages of runner bean plants of varieties A and B affected by pests and diseases during one particular growing season.In total thehorticulturalist receives reports from 8 gardeners growing variety A and from 12 gardeners growing variety B. (Each gardener only grows one of the varieties so the data are not paired. Also each gardener reports only one percentage.) Using the procedure for a two-sample t-test, the test statistic turns out to be 2.44.

What is the value of the critical value at the 5% significance level that this test statistic should be compared with? (Give your answer to three decimal places.)