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Finding the Fourth Proportional to 931.89, 1,285.47 and 861.90

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Solution

The fourth proportional to 931.89, 1,285.47 and 861.90 is: 1,188.92

Step by Step Solution

  1. Step 1: Write the proportion equation
    931.89 : 1,285.47 = 861.90 : x
  2. Step 2: Convert to fraction form
    931.89/1,285.47 = 861.90/x
  3. Step 3: Cross multiply
    931.89x = 1,285.47 × 861.90
  4. Step 4: Simplify right side
    931.89x = 1,107,946.59
  5. Step 5: Solve for x
    x = 1,107,946.59/931.89
  6. Step 6: Final answer
    x = 1,188.92

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1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.