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Finding the Fourth Proportional to 915.36, 1,370.40 and 685.28

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Solution

The fourth proportional to 915.36, 1,370.40 and 685.28 is: 1,025.94

Step by Step Solution

  1. Step 1: Write the proportion equation
    915.36 : 1,370.40 = 685.28 : x
  2. Step 2: Convert to fraction form
    915.36/1,370.40 = 685.28/x
  3. Step 3: Cross multiply
    915.36x = 1,370.40 × 685.28
  4. Step 4: Simplify right side
    915.36x = 939,107.71
  5. Step 5: Solve for x
    x = 939,107.71/915.36
  6. Step 6: Final answer
    x = 1,025.94

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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.