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Finding the Fourth Proportional to 720, 991.17 and 646.29

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Solution

The fourth proportional to 720, 991.17 and 646.29 is: 889.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    720 : 991.17 = 646.29 : x
  2. Step 2: Convert to fraction form
    720/991.17 = 646.29/x
  3. Step 3: Cross multiply
    720x = 991.17 × 646.29
  4. Step 4: Simplify right side
    720x = 640,583.26
  5. Step 5: Solve for x
    x = 640,583.26/720
  6. Step 6: Final answer
    x = 889.70

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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.