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Finding the Fourth Proportional to 816.51, 1,126.80 and 639.69

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Solution

The fourth proportional to 816.51, 1,126.80 and 639.69 is: 882.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    816.51 : 1,126.80 = 639.69 : x
  2. Step 2: Convert to fraction form
    816.51/1,126.80 = 639.69/x
  3. Step 3: Cross multiply
    816.51x = 1,126.80 × 639.69
  4. Step 4: Simplify right side
    816.51x = 720,802.69
  5. Step 5: Solve for x
    x = 720,802.69/816.51
  6. Step 6: Final answer
    x = 882.78

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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.