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Finding the Fourth Proportional to 1,151.64, 1,728.90 and 639

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Solution

The fourth proportional to 1,151.64, 1,728.90 and 639 is: 959.30

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,151.64 : 1,728.90 = 639 : x
  2. Step 2: Convert to fraction form
    1,151.64/1,728.90 = 639/x
  3. Step 3: Cross multiply
    1,151.64x = 1,728.90 × 639
  4. Step 4: Simplify right side
    1,151.64x = 1,104,767.10
  5. Step 5: Solve for x
    x = 1,104,767.10/1,151.64
  6. Step 6: Final answer
    x = 959.30

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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.