Final answer:
To find the length of the picture frame whose width is 3 inches and has the same proportions as a 9-inch wide by 15-inch long frame, we can set up a proportion: 3 / x = 9 / 15. Solving for 'x', the length of the picture frame is 5 inches.
Step-by-step explanation:
To find the length of a picture frame whose width is 3 inches and has the same proportions as a 9-inch wide by 15-inch long frame, we can set up a proportion.
Let 'x' be the length of the picture frame we want to find.
Using the proportion: (width of first frame) / (length of first frame) = (width of second frame) / (length of second frame), we can write:
3 / x = 9 / 15
Cross-multiplying and solving for 'x', we get:
x = (3 * 15) / 9 = 5 inches