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Finding the Fourth Proportional to 991.77, 1,368.14 and 642.39

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Solution

The fourth proportional to 991.77, 1,368.14 and 642.39 is: 886.17

Step by Step Solution

  1. Step 1: Write the proportion equation
    991.77 : 1,368.14 = 642.39 : x
  2. Step 2: Convert to fraction form
    991.77/1,368.14 = 642.39/x
  3. Step 3: Cross multiply
    991.77x = 1,368.14 × 642.39
  4. Step 4: Simplify right side
    991.77x = 878,876.24
  5. Step 5: Solve for x
    x = 878,876.24/991.77
  6. Step 6: Final answer
    x = 886.17

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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.