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Finding the Fourth Proportional to 947.28, 1,421.38 and 427.64

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Solution

The fourth proportional to 947.28, 1,421.38 and 427.64 is: 641.67

Step by Step Solution

  1. Step 1: Write the proportion equation
    947.28 : 1,421.38 = 427.64 : x
  2. Step 2: Convert to fraction form
    947.28/1,421.38 = 427.64/x
  3. Step 3: Cross multiply
    947.28x = 1,421.38 × 427.64
  4. Step 4: Simplify right side
    947.28x = 607,838.94
  5. Step 5: Solve for x
    x = 607,838.94/947.28
  6. Step 6: Final answer
    x = 641.67

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.