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Finding the Fourth Proportional to 985.56, 1,478.86 and 638.81

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Solution

The fourth proportional to 985.56, 1,478.86 and 638.81 is: 958.54

Step by Step Solution

  1. Step 1: Write the proportion equation
    985.56 : 1,478.86 = 638.81 : x
  2. Step 2: Convert to fraction form
    985.56/1,478.86 = 638.81/x
  3. Step 3: Cross multiply
    985.56x = 1,478.86 × 638.81
  4. Step 4: Simplify right side
    985.56x = 944,701.57
  5. Step 5: Solve for x
    x = 944,701.57/985.56
  6. Step 6: Final answer
    x = 958.54

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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.