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Finding the Fourth Proportional to 918.30, 1,375.85 and 643.86

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Solution

The fourth proportional to 918.30, 1,375.85 and 643.86 is: 964.67

Step by Step Solution

  1. Step 1: Write the proportion equation
    918.30 : 1,375.85 = 643.86 : x
  2. Step 2: Convert to fraction form
    918.30/1,375.85 = 643.86/x
  3. Step 3: Cross multiply
    918.30x = 1,375.85 × 643.86
  4. Step 4: Simplify right side
    918.30x = 885,856.39
  5. Step 5: Solve for x
    x = 885,856.39/918.30
  6. Step 6: Final answer
    x = 964.67

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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.