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Finding the Fourth Proportional to 1,091.91, 1,638.30 and 398.63

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Solution

The fourth proportional to 1,091.91, 1,638.30 and 398.63 is: 598.10

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,091.91 : 1,638.30 = 398.63 : x
  2. Step 2: Convert to fraction form
    1,091.91/1,638.30 = 398.63/x
  3. Step 3: Cross multiply
    1,091.91x = 1,638.30 × 398.63
  4. Step 4: Simplify right side
    1,091.91x = 653,075.53
  5. Step 5: Solve for x
    x = 653,075.53/1,091.91
  6. Step 6: Final answer
    x = 598.10

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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.