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Finding the Fourth Proportional to 715.36, 987.36 and 420.64

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Solution

The fourth proportional to 715.36, 987.36 and 420.64 is: 580.58

Step by Step Solution

  1. Step 1: Write the proportion equation
    715.36 : 987.36 = 420.64 : x
  2. Step 2: Convert to fraction form
    715.36/987.36 = 420.64/x
  3. Step 3: Cross multiply
    715.36x = 987.36 × 420.64
  4. Step 4: Simplify right side
    715.36x = 415,323.11
  5. Step 5: Solve for x
    x = 415,323.11/715.36
  6. Step 6: Final answer
    x = 580.58

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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.