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Finding the Fourth Proportional to 1,328.40, 1,991.12 and 587.78

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Solution

The fourth proportional to 1,328.40, 1,991.12 and 587.78 is: 881.02

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,328.40 : 1,991.12 = 587.78 : x
  2. Step 2: Convert to fraction form
    1,328.40/1,991.12 = 587.78/x
  3. Step 3: Cross multiply
    1,328.40x = 1,991.12 × 587.78
  4. Step 4: Simplify right side
    1,328.40x = 1,170,343.17
  5. Step 5: Solve for x
    x = 1,170,343.17/1,328.40
  6. Step 6: Final answer
    x = 881.02

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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.