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Finding the Fourth Proportional to 875.22, 1,207.65 and 642.90

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Solution

The fourth proportional to 875.22, 1,207.65 and 642.90 is: 887.09

Step by Step Solution

  1. Step 1: Write the proportion equation
    875.22 : 1,207.65 = 642.90 : x
  2. Step 2: Convert to fraction form
    875.22/1,207.65 = 642.90/x
  3. Step 3: Cross multiply
    875.22x = 1,207.65 × 642.90
  4. Step 4: Simplify right side
    875.22x = 776,398.19
  5. Step 5: Solve for x
    x = 776,398.19/875.22
  6. Step 6: Final answer
    x = 887.09

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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.