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Finding the Fourth Proportional to 715.40, 987.22 and 420.60

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Solution

The fourth proportional to 715.40, 987.22 and 420.60 is: 580.41

Step by Step Solution

  1. Step 1: Write the proportion equation
    715.40 : 987.22 = 420.60 : x
  2. Step 2: Convert to fraction form
    715.40/987.22 = 420.60/x
  3. Step 3: Cross multiply
    715.40x = 987.22 × 420.60
  4. Step 4: Simplify right side
    715.40x = 415,224.73
  5. Step 5: Solve for x
    x = 415,224.73/715.40
  6. Step 6: Final answer
    x = 580.41

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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.