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Finding the Fourth Proportional to 780.63, 1,076.40 and 631.59

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Solution

The fourth proportional to 780.63, 1,076.40 and 631.59 is: 870.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    780.63 : 1,076.40 = 631.59 : x
  2. Step 2: Convert to fraction form
    780.63/1,076.40 = 631.59/x
  3. Step 3: Cross multiply
    780.63x = 1,076.40 × 631.59
  4. Step 4: Simplify right side
    780.63x = 679,843.48
  5. Step 5: Solve for x
    x = 679,843.48/780.63
  6. Step 6: Final answer
    x = 870.89

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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.