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Finding the Fourth Proportional to 1,280, 1,918.86 and 731.40

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Solution

The fourth proportional to 1,280, 1,918.86 and 731.40 is: 1,096.45

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,280 : 1,918.86 = 731.40 : x
  2. Step 2: Convert to fraction form
    1,280/1,918.86 = 731.40/x
  3. Step 3: Cross multiply
    1,280x = 1,918.86 × 731.40
  4. Step 4: Simplify right side
    1,280x = 1,403,454.20
  5. Step 5: Solve for x
    x = 1,403,454.20/1,280
  6. Step 6: Final answer
    x = 1,096.45

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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.