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Finding the Fourth Proportional to 908.40, 1,361.60 and 691.28

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Solution

The fourth proportional to 908.40, 1,361.60 and 691.28 is: 1,036.16

Step by Step Solution

  1. Step 1: Write the proportion equation
    908.40 : 1,361.60 = 691.28 : x
  2. Step 2: Convert to fraction form
    908.40/1,361.60 = 691.28/x
  3. Step 3: Cross multiply
    908.40x = 1,361.60 × 691.28
  4. Step 4: Simplify right side
    908.40x = 941,246.85
  5. Step 5: Solve for x
    x = 941,246.85/908.40
  6. Step 6: Final answer
    x = 1,036.16

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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.