You are checking the intermediate results of a phone app that caculates the weight of an object

(sin 42)/31. = sinx)/37

sinx = 37 (sin42)/31

= 37× 0.66/31 = 0.787

x= 51.9

other angle opposite to y = 180-51.9-42

= 180- 93.9 =86.1

so

sin42)/31 = sin 86.1)/y

0.021 = 0.997 /y

y= 0.997/0.021 =47.47

i believe your answer is 99.7% of 7-year-old children are between 46.6 inches and 49.5 inches tall.