O Growth Spurt: It is generally known that boys grow at an unusually fast rate between the ages of about 12 and 14. Following are heights, in inches of 10 boys, measured at age 12 and again at age 14. Age 12 Age 14 62.7 67.5 67.5 73.7 59.2 64.9 61.4 67.0 60.7 65.5 55.9 62.1 59.7 65.4 56.3 61.5 63.0 68.5 58.6 63.9