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Finding the Fourth Proportional to 787.80, 1,087.20 and 438.51

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Solution

The fourth proportional to 787.80, 1,087.20 and 438.51 is: 605.16

Step by Step Solution

  1. Step 1: Write the proportion equation
    787.80 : 1,087.20 = 438.51 : x
  2. Step 2: Convert to fraction form
    787.80/1,087.20 = 438.51/x
  3. Step 3: Cross multiply
    787.80x = 1,087.20 × 438.51
  4. Step 4: Simplify right side
    787.80x = 476,748.07
  5. Step 5: Solve for x
    x = 476,748.07/787.80
  6. Step 6: Final answer
    x = 605.16

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.