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Finding the Fourth Proportional to 818.90, 1,129.36 and 643.94

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Solution

The fourth proportional to 818.90, 1,129.36 and 643.94 is: 888.07

Step by Step Solution

  1. Step 1: Write the proportion equation
    818.90 : 1,129.36 = 643.94 : x
  2. Step 2: Convert to fraction form
    818.90/1,129.36 = 643.94/x
  3. Step 3: Cross multiply
    818.90x = 1,129.36 × 643.94
  4. Step 4: Simplify right side
    818.90x = 727,240.08
  5. Step 5: Solve for x
    x = 727,240.08/818.90
  6. Step 6: Final answer
    x = 888.07

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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.