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Finding the Fourth Proportional to 684.90, 945.21 and 390.13

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Solution

The fourth proportional to 684.90, 945.21 and 390.13 is: 538.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    684.90 : 945.21 = 390.13 : x
  2. Step 2: Convert to fraction form
    684.90/945.21 = 390.13/x
  3. Step 3: Cross multiply
    684.90x = 945.21 × 390.13
  4. Step 4: Simplify right side
    684.90x = 368,754.78
  5. Step 5: Solve for x
    x = 368,754.78/684.90
  6. Step 6: Final answer
    x = 538.40

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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.