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Finding the Fourth Proportional to 1,224.12, 1,689.68 and 783.21

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Solution

The fourth proportional to 1,224.12, 1,689.68 and 783.21 is: 1,081.08

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,224.12 : 1,689.68 = 783.21 : x
  2. Step 2: Convert to fraction form
    1,224.12/1,689.68 = 783.21/x
  3. Step 3: Cross multiply
    1,224.12x = 1,689.68 × 783.21
  4. Step 4: Simplify right side
    1,224.12x = 1,323,374.27
  5. Step 5: Solve for x
    x = 1,323,374.27/1,224.12
  6. Step 6: Final answer
    x = 1,081.08

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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.