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Finding the Fourth Proportional to 865.40, 1,292.05 and 856.28

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Solution

The fourth proportional to 865.40, 1,292.05 and 856.28 is: 1,278.43

Step by Step Solution

  1. Step 1: Write the proportion equation
    865.40 : 1,292.05 = 856.28 : x
  2. Step 2: Convert to fraction form
    865.40/1,292.05 = 856.28/x
  3. Step 3: Cross multiply
    865.40x = 1,292.05 × 856.28
  4. Step 4: Simplify right side
    865.40x = 1,106,356.57
  5. Step 5: Solve for x
    x = 1,106,356.57/865.40
  6. Step 6: Final answer
    x = 1,278.43

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1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.