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Finding the Fourth Proportional to 685.55, 946.14 and 390.81

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Solution

The fourth proportional to 685.55, 946.14 and 390.81 is: 539.36

Step by Step Solution

  1. Step 1: Write the proportion equation
    685.55 : 946.14 = 390.81 : x
  2. Step 2: Convert to fraction form
    685.55/946.14 = 390.81/x
  3. Step 3: Cross multiply
    685.55x = 946.14 × 390.81
  4. Step 4: Simplify right side
    685.55x = 369,760.97
  5. Step 5: Solve for x
    x = 369,760.97/685.55
  6. Step 6: Final answer
    x = 539.36

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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.