Which of these is a true proportion?
Show the answer
Answer: D
Correct answer:
In a true proportion the cross products are equal. For 6/8 and 15/20:
so the ratios are equal (both reduce to 3/4).
- A: Cross products are 6 × 12 = 72 and 9 × 10 = 90, which are not equal.
- B: Cross products are 4 × 16 = 64 and 5 × 12 = 60, which are not equal.
- C: Cross products are 3 × 14 = 42 and 7 × 9 = 63; the numerator was tripled but the denominator only doubled.
- D (correct): Cross products are 6 × 20 = 120 and 8 × 15 = 120, which are equal.