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Finding the Fourth Proportional to 685.55, 946.01 and 390.78

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Solution

The fourth proportional to 685.55, 946.01 and 390.78 is: 539.25

Step by Step Solution

  1. Step 1: Write the proportion equation
    685.55 : 946.01 = 390.78 : x
  2. Step 2: Convert to fraction form
    685.55/946.01 = 390.78/x
  3. Step 3: Cross multiply
    685.55x = 946.01 × 390.78
  4. Step 4: Simplify right side
    685.55x = 369,682.76
  5. Step 5: Solve for x
    x = 369,682.76/685.55
  6. Step 6: Final answer
    x = 539.25

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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.