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Finding the Fourth Proportional to 1,008.60, 1,390.87 and 787.47

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Solution

The fourth proportional to 1,008.60, 1,390.87 and 787.47 is: 1,085.93

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,008.60 : 1,390.87 = 787.47 : x
  2. Step 2: Convert to fraction form
    1,008.60/1,390.87 = 787.47/x
  3. Step 3: Cross multiply
    1,008.60x = 1,390.87 × 787.47
  4. Step 4: Simplify right side
    1,008.60x = 1,095,268.40
  5. Step 5: Solve for x
    x = 1,095,268.40/1,008.60
  6. Step 6: Final answer
    x = 1,085.93

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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.