7.22 A final one-sample t test. The one-sample t statistic for testing

H₀: μ = 20

H_a: μ < 20

based on observations has the value .

1. (a) What are the degrees of freedom for this statistic?

2. (b) Between what two values does the P-value of the test fall?

3. (c) If you have software available, find the exact P-value.