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Finding the Fourth Proportional to 813.68, 1,123.84 and 638.80

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Solution

The fourth proportional to 813.68, 1,123.84 and 638.80 is: 882.30

Step by Step Solution

  1. Step 1: Write the proportion equation
    813.68 : 1,123.84 = 638.80 : x
  2. Step 2: Convert to fraction form
    813.68/1,123.84 = 638.80/x
  3. Step 3: Cross multiply
    813.68x = 1,123.84 × 638.80
  4. Step 4: Simplify right side
    813.68x = 717,908.99
  5. Step 5: Solve for x
    x = 717,908.99/813.68
  6. Step 6: Final answer
    x = 882.30

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1.5x scale

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.