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Finding the Fourth Proportional to 938.79, 1,405.35 and 678.38

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Solution

The fourth proportional to 938.79, 1,405.35 and 678.38 is: 1,015.51

Step by Step Solution

  1. Step 1: Write the proportion equation
    938.79 : 1,405.35 = 678.38 : x
  2. Step 2: Convert to fraction form
    938.79/1,405.35 = 678.38/x
  3. Step 3: Cross multiply
    938.79x = 1,405.35 × 678.38
  4. Step 4: Simplify right side
    938.79x = 953,354.31
  5. Step 5: Solve for x
    x = 953,354.31/938.79
  6. Step 6: Final answer
    x = 1,015.51

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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.