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Finding the Fourth Proportional to 685.66, 946.21 and 390.93

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Solution

The fourth proportional to 685.66, 946.21 and 390.93 is: 539.48

Step by Step Solution

  1. Step 1: Write the proportion equation
    685.66 : 946.21 = 390.93 : x
  2. Step 2: Convert to fraction form
    685.66/946.21 = 390.93/x
  3. Step 3: Cross multiply
    685.66x = 946.21 × 390.93
  4. Step 4: Simplify right side
    685.66x = 369,901.88
  5. Step 5: Solve for x
    x = 369,901.88/685.66
  6. Step 6: Final answer
    x = 539.48

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Double scale
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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.