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Finding the Fourth Proportional to 685.40, 1,028 and 315.10

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Solution

The fourth proportional to 685.40, 1,028 and 315.10 is: 472.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    685.40 : 1,028 = 315.10 : x
  2. Step 2: Convert to fraction form
    685.40/1,028 = 315.10/x
  3. Step 3: Cross multiply
    685.40x = 1,028 × 315.10
  4. Step 4: Simplify right side
    685.40x = 323,922.80
  5. Step 5: Solve for x
    x = 323,922.80/685.40
  6. Step 6: Final answer
    x = 472.60

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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.