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Finding the Fourth Proportional to 991.20, 1,493.40 and 912.48

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Solution

The fourth proportional to 991.20, 1,493.40 and 912.48 is: 1,374.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    991.20 : 1,493.40 = 912.48 : x
  2. Step 2: Convert to fraction form
    991.20/1,493.40 = 912.48/x
  3. Step 3: Cross multiply
    991.20x = 1,493.40 × 912.48
  4. Step 4: Simplify right side
    991.20x = 1,362,697.63
  5. Step 5: Solve for x
    x = 1,362,697.63/991.20
  6. Step 6: Final answer
    x = 1,374.80

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.