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Finding the Fourth Proportional to 684.87, 945.12 and 390.21

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Solution

The fourth proportional to 684.87, 945.12 and 390.21 is: 538.49

Step by Step Solution

  1. Step 1: Write the proportion equation
    684.87 : 945.12 = 390.21 : x
  2. Step 2: Convert to fraction form
    684.87/945.12 = 390.21/x
  3. Step 3: Cross multiply
    684.87x = 945.12 × 390.21
  4. Step 4: Simplify right side
    684.87x = 368,795.28
  5. Step 5: Solve for x
    x = 368,795.28/684.87
  6. Step 6: Final answer
    x = 538.49

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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.