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Finding the Fourth Proportional to 686.42, 947.18 and 391.63

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Solution

The fourth proportional to 686.42, 947.18 and 391.63 is: 540.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    686.42 : 947.18 = 391.63 : x
  2. Step 2: Convert to fraction form
    686.42/947.18 = 391.63/x
  3. Step 3: Cross multiply
    686.42x = 947.18 × 391.63
  4. Step 4: Simplify right side
    686.42x = 370,939.37
  5. Step 5: Solve for x
    x = 370,939.37/686.42
  6. Step 6: Final answer
    x = 540.40

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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.