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Finding the Fourth Proportional to 840, 1,157.58 and 642.36

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Solution

The fourth proportional to 840, 1,157.58 and 642.36 is: 885.22

Step by Step Solution

  1. Step 1: Write the proportion equation
    840 : 1,157.58 = 642.36 : x
  2. Step 2: Convert to fraction form
    840/1,157.58 = 642.36/x
  3. Step 3: Cross multiply
    840x = 1,157.58 × 642.36
  4. Step 4: Simplify right side
    840x = 743,583.09
  5. Step 5: Solve for x
    x = 743,583.09/840
  6. Step 6: Final answer
    x = 885.22

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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.