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Finding the Fourth Proportional to 687.69, 948.86 and 407.78

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Solution

The fourth proportional to 687.69, 948.86 and 407.78 is: 562.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    687.69 : 948.86 = 407.78 : x
  2. Step 2: Convert to fraction form
    687.69/948.86 = 407.78/x
  3. Step 3: Cross multiply
    687.69x = 948.86 × 407.78
  4. Step 4: Simplify right side
    687.69x = 386,926.13
  5. Step 5: Solve for x
    x = 386,926.13/687.69
  6. Step 6: Final answer
    x = 562.65

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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.