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Finding the Fourth Proportional to 1,218.90, 1,681.92 and 721.34

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Solution

The fourth proportional to 1,218.90, 1,681.92 and 721.34 is: 995.35

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,218.90 : 1,681.92 = 721.34 : x
  2. Step 2: Convert to fraction form
    1,218.90/1,681.92 = 721.34/x
  3. Step 3: Cross multiply
    1,218.90x = 1,681.92 × 721.34
  4. Step 4: Simplify right side
    1,218.90x = 1,213,236.17
  5. Step 5: Solve for x
    x = 1,213,236.17/1,218.90
  6. Step 6: Final answer
    x = 995.35

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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.