With 100 pennies, we have 99 degrees of freedom for the mean. Although Table 4.4.34.4.3\PageIndex{3} does not include a value for t(0.05, 99), we can approximate its value by using the values for t(0.05, 60) and t(0.05, 100) and by assuming a linear change in its value. t(0.05,99)=t(0.05,60)−3940{t(0.05,60)−t(0.05,100})t(0.05,99)=t(0.05,60)−3940{t(0.05,60)−t(0.05,100})t(0.05, 99) = t(0.05, 60) - \frac {39} {40} \left\{ t(0.05, 60) - t(0.05, 100\} \right) \nonumber t(0.05,99)=2.000−3940{2.000−1.984}=1.9844t(0.05,99)=2.000−3940{2.000−1.984}=1.9844