Multiple choice

What is the ratio of the third proportional to 0.4 and 0.8, to the mean proportional between 13.5 and 0.24?

  1. 5 : 4

  2. 7 : 8

  3. 8 : 9

  4. 9 : 10

Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Third proportional of 0.4 and 0.8 is (0.8×0.8)/0.4 = 1.6. Mean proportional between 13.5 and 0.24 is sqrt(13.5×0.24) = sqrt(3.24) = 1.8. Ratio = 1.6:1.8 = 16:18 = 8:9. The question has an image but is solvable without it.