Calculate the distance between the points P(2, 2) and Q(5, 4) correct to three significant figures.

∵ Distance between the given points = $\sqrt{(x$2 - x1)^2 + (y2 - y1)^2}

Distance between P(2, 2) and Q(5, 4):

$= \sqrt{(5 - 2)^2 + (4 - 2)^2}\\[1em] = \sqrt{3^2 + 2^2}\\[1em] = \sqrt{9 + 4}\\[1em] = \sqrt{13}\\[1em] = 3.605 \text{ units}$

Hence, the distance between the points P(2, 2) and Q(5, 4) is 3.605 units.