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Finding the Fourth Proportional to 905.40, 1,355.08 and 687.76

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Solution

The fourth proportional to 905.40, 1,355.08 and 687.76 is: 1,029.35

Step by Step Solution

  1. Step 1: Write the proportion equation
    905.40 : 1,355.08 = 687.76 : x
  2. Step 2: Convert to fraction form
    905.40/1,355.08 = 687.76/x
  3. Step 3: Cross multiply
    905.40x = 1,355.08 × 687.76
  4. Step 4: Simplify right side
    905.40x = 931,969.82
  5. Step 5: Solve for x
    x = 931,969.82/905.40
  6. Step 6: Final answer
    x = 1,029.35

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.