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Finding the Fourth Proportional to 715.80, 987.56 and 420.96

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Solution

The fourth proportional to 715.80, 987.56 and 420.96 is: 580.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    715.80 : 987.56 = 420.96 : x
  2. Step 2: Convert to fraction form
    715.80/987.56 = 420.96/x
  3. Step 3: Cross multiply
    715.80x = 987.56 × 420.96
  4. Step 4: Simplify right side
    715.80x = 415,723.26
  5. Step 5: Solve for x
    x = 415,723.26/715.80
  6. Step 6: Final answer
    x = 580.78

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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.