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Finding the Fourth Proportional to 1,035.40, 1,428.42 and 685.64

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Solution

The fourth proportional to 1,035.40, 1,428.42 and 685.64 is: 945.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,035.40 : 1,428.42 = 685.64 : x
  2. Step 2: Convert to fraction form
    1,035.40/1,428.42 = 685.64/x
  3. Step 3: Cross multiply
    1,035.40x = 1,428.42 × 685.64
  4. Step 4: Simplify right side
    1,035.40x = 979,381.89
  5. Step 5: Solve for x
    x = 979,381.89/1,035.40
  6. Step 6: Final answer
    x = 945.90

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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.