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Finding the Fourth Proportional to 1,328.72, 1,988.04 and 781.16

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Solution

The fourth proportional to 1,328.72, 1,988.04 and 781.16 is: 1,168.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,328.72 : 1,988.04 = 781.16 : x
  2. Step 2: Convert to fraction form
    1,328.72/1,988.04 = 781.16/x
  3. Step 3: Cross multiply
    1,328.72x = 1,988.04 × 781.16
  4. Step 4: Simplify right side
    1,328.72x = 1,552,977.33
  5. Step 5: Solve for x
    x = 1,552,977.33/1,328.72
  6. Step 6: Final answer
    x = 1,168.78

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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.