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Finding the Fourth Proportional to 685.71, 945.98 and 420.05

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Solution

The fourth proportional to 685.71, 945.98 and 420.05 is: 579.49

Step by Step Solution

  1. Step 1: Write the proportion equation
    685.71 : 945.98 = 420.05 : x
  2. Step 2: Convert to fraction form
    685.71/945.98 = 420.05/x
  3. Step 3: Cross multiply
    685.71x = 945.98 × 420.05
  4. Step 4: Simplify right side
    685.71x = 397,358.90
  5. Step 5: Solve for x
    x = 397,358.90/685.71
  6. Step 6: Final answer
    x = 579.49

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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.