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Finding the Fourth Proportional to 991.96, 1,368.33 and 642.66

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Solution

The fourth proportional to 991.96, 1,368.33 and 642.66 is: 886.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    991.96 : 1,368.33 = 642.66 : x
  2. Step 2: Convert to fraction form
    991.96/1,368.33 = 642.66/x
  3. Step 3: Cross multiply
    991.96x = 1,368.33 × 642.66
  4. Step 4: Simplify right side
    991.96x = 879,370.96
  5. Step 5: Solve for x
    x = 879,370.96/991.96
  6. Step 6: Final answer
    x = 886.50

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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.