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Finding the Fourth Proportional to 991.20, 1,364.40 and 904.80

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Solution

The fourth proportional to 991.20, 1,364.40 and 904.80 is: 1,245.47

Step by Step Solution

  1. Step 1: Write the proportion equation
    991.20 : 1,364.40 = 904.80 : x
  2. Step 2: Convert to fraction form
    991.20/1,364.40 = 904.80/x
  3. Step 3: Cross multiply
    991.20x = 1,364.40 × 904.80
  4. Step 4: Simplify right side
    991.20x = 1,234,509.12
  5. Step 5: Solve for x
    x = 1,234,509.12/991.20
  6. Step 6: Final answer
    x = 1,245.47

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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.