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Finding the Fourth Proportional to 991.89, 1,365.68 and 842.21

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Solution

The fourth proportional to 991.89, 1,365.68 and 842.21 is: 1,159.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    991.89 : 1,365.68 = 842.21 : x
  2. Step 2: Convert to fraction form
    991.89/1,365.68 = 842.21/x
  3. Step 3: Cross multiply
    991.89x = 1,365.68 × 842.21
  4. Step 4: Simplify right side
    991.89x = 1,150,195.06
  5. Step 5: Solve for x
    x = 1,150,195.06/991.89
  6. Step 6: Final answer
    x = 1,159.60

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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.