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Finding the Fourth Proportional to 991.80, 1,368.63 and 618.66

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Solution

The fourth proportional to 991.80, 1,368.63 and 618.66 is: 853.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    991.80 : 1,368.63 = 618.66 : x
  2. Step 2: Convert to fraction form
    991.80/1,368.63 = 618.66/x
  3. Step 3: Cross multiply
    991.80x = 1,368.63 × 618.66
  4. Step 4: Simplify right side
    991.80x = 846,716.64
  5. Step 5: Solve for x
    x = 846,716.64/991.80
  6. Step 6: Final answer
    x = 853.72

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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.