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Finding the Fourth Proportional to 939.79, 1,406.72 and 840.74

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Solution

The fourth proportional to 939.79, 1,406.72 and 840.74 is: 1,258.45

Step by Step Solution

  1. Step 1: Write the proportion equation
    939.79 : 1,406.72 = 840.74 : x
  2. Step 2: Convert to fraction form
    939.79/1,406.72 = 840.74/x
  3. Step 3: Cross multiply
    939.79x = 1,406.72 × 840.74
  4. Step 4: Simplify right side
    939.79x = 1,182,682.42
  5. Step 5: Solve for x
    x = 1,182,682.42/939.79
  6. Step 6: Final answer
    x = 1,258.45

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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.