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Finding the Fourth Proportional to 685.45, 945.98 and 390.74

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Solution

The fourth proportional to 685.45, 945.98 and 390.74 is: 539.25

Step by Step Solution

  1. Step 1: Write the proportion equation
    685.45 : 945.98 = 390.74 : x
  2. Step 2: Convert to fraction form
    685.45/945.98 = 390.74/x
  3. Step 3: Cross multiply
    685.45x = 945.98 × 390.74
  4. Step 4: Simplify right side
    685.45x = 369,630.27
  5. Step 5: Solve for x
    x = 369,630.27/685.45
  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.