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Finding the Fourth Proportional to 1,392, 1,920.96 and 840.32

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Solution

The fourth proportional to 1,392, 1,920.96 and 840.32 is: 1,159.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,392 : 1,920.96 = 840.32 : x
  2. Step 2: Convert to fraction form
    1,392/1,920.96 = 840.32/x
  3. Step 3: Cross multiply
    1,392x = 1,920.96 × 840.32
  4. Step 4: Simplify right side
    1,392x = 1,614,221.11
  5. Step 5: Solve for x
    x = 1,614,221.11/1,392
  6. Step 6: Final answer
    x = 1,159.64

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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.