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Finding the Fourth Proportional to 1,387.88, 1,916.16 and 864.68

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Solution

The fourth proportional to 1,387.88, 1,916.16 and 864.68 is: 1,193.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,387.88 : 1,916.16 = 864.68 : x
  2. Step 2: Convert to fraction form
    1,387.88/1,916.16 = 864.68/x
  3. Step 3: Cross multiply
    1,387.88x = 1,916.16 × 864.68
  4. Step 4: Simplify right side
    1,387.88x = 1,656,865.23
  5. Step 5: Solve for x
    x = 1,656,865.23/1,387.88
  6. Step 6: Final answer
    x = 1,193.81

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1.5x scale

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.