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Finding the Fourth Proportional to 1,238.91, 1,709.39 and 686.91

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Solution

The fourth proportional to 1,238.91, 1,709.39 and 686.91 is: 947.77

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,238.91 : 1,709.39 = 686.91 : x
  2. Step 2: Convert to fraction form
    1,238.91/1,709.39 = 686.91/x
  3. Step 3: Cross multiply
    1,238.91x = 1,709.39 × 686.91
  4. Step 4: Simplify right side
    1,238.91x = 1,174,197.08
  5. Step 5: Solve for x
    x = 1,174,197.08/1,238.91
  6. Step 6: Final answer
    x = 947.77

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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.