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Finding the Fourth Proportional to 715.43, 987.34 and 420.75

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Solution

The fourth proportional to 715.43, 987.34 and 420.75 is: 580.66

Step by Step Solution

  1. Step 1: Write the proportion equation
    715.43 : 987.34 = 420.75 : x
  2. Step 2: Convert to fraction form
    715.43/987.34 = 420.75/x
  3. Step 3: Cross multiply
    715.43x = 987.34 × 420.75
  4. Step 4: Simplify right side
    715.43x = 415,423.31
  5. Step 5: Solve for x
    x = 415,423.31/715.43
  6. Step 6: Final answer
    x = 580.66

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Double scale
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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.