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Finding the Fourth Proportional to 1,218.32, 1,681.50 and 721.20

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Solution

The fourth proportional to 1,218.32, 1,681.50 and 721.20 is: 995.39

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,218.32 : 1,681.50 = 721.20 : x
  2. Step 2: Convert to fraction form
    1,218.32/1,681.50 = 721.20/x
  3. Step 3: Cross multiply
    1,218.32x = 1,681.50 × 721.20
  4. Step 4: Simplify right side
    1,218.32x = 1,212,701.74
  5. Step 5: Solve for x
    x = 1,212,701.74/1,218.32
  6. Step 6: Final answer
    x = 995.39

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1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.