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Finding the Fourth Proportional to 686.55, 946.90 and 420.77

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Solution

The fourth proportional to 686.55, 946.90 and 420.77 is: 580.33

Step by Step Solution

  1. Step 1: Write the proportion equation
    686.55 : 946.90 = 420.77 : x
  2. Step 2: Convert to fraction form
    686.55/946.90 = 420.77/x
  3. Step 3: Cross multiply
    686.55x = 946.90 × 420.77
  4. Step 4: Simplify right side
    686.55x = 398,427.11
  5. Step 5: Solve for x
    x = 398,427.11/686.55
  6. Step 6: Final answer
    x = 580.33

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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.