Leslie is blowing up one of her favorite photographs to
hang on her wall. If the
photo's original length and
height were 8 inches and 15 inches, and the new height is 4 feet, how many feet must the new picture be?
Since the new height is 4 feet, and there are 12 inches in a foot, the new height of the picture must be 4 * 12 = <<4*12=48>>48 inches.
Since the original height of the picture is 15 inches, the new picture must be 48 / 15 = <<48/15=3.2>>3.2 times larger.
The new length of the picture must be 8 inches * 3.2 = <<8*3.2=25.6>>25.6 inches.
Since there are 12 inches in a foot, the new picture must be 25.6 / 12 = <<25.6/12=2.13>>2.13 feet long. Answer: \boxed{2.13}.