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Finding the Fourth Proportional to 918.84, 1,378 and 485.76

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Solution

The fourth proportional to 918.84, 1,378 and 485.76 is: 728.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    918.84 : 1,378 = 485.76 : x
  2. Step 2: Convert to fraction form
    918.84/1,378 = 485.76/x
  3. Step 3: Cross multiply
    918.84x = 1,378 × 485.76
  4. Step 4: Simplify right side
    918.84x = 669,377.28
  5. Step 5: Solve for x
    x = 669,377.28/918.84
  6. Step 6: Final answer
    x = 728.50

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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.