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Finding the Fourth Proportional to 788.40, 1,089.02 and 639.58

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Solution

The fourth proportional to 788.40, 1,089.02 and 639.58 is: 883.45

Step by Step Solution

  1. Step 1: Write the proportion equation
    788.40 : 1,089.02 = 639.58 : x
  2. Step 2: Convert to fraction form
    788.40/1,089.02 = 639.58/x
  3. Step 3: Cross multiply
    788.40x = 1,089.02 × 639.58
  4. Step 4: Simplify right side
    788.40x = 696,514.53
  5. Step 5: Solve for x
    x = 696,514.53/788.40
  6. Step 6: Final answer
    x = 883.45

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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.