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Finding the Fourth Proportional to 687.42, 947.07 and 621.90

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Solution

The fourth proportional to 687.42, 947.07 and 621.90 is: 856.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    687.42 : 947.07 = 621.90 : x
  2. Step 2: Convert to fraction form
    687.42/947.07 = 621.90/x
  3. Step 3: Cross multiply
    687.42x = 947.07 × 621.90
  4. Step 4: Simplify right side
    687.42x = 588,982.83
  5. Step 5: Solve for x
    x = 588,982.83/687.42
  6. Step 6: Final answer
    x = 856.80

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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.