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Finding the Fourth Proportional to 918.60, 1,373.90 and 821.80

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Solution

The fourth proportional to 918.60, 1,373.90 and 821.80 is: 1,229.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    918.60 : 1,373.90 = 821.80 : x
  2. Step 2: Convert to fraction form
    918.60/1,373.90 = 821.80/x
  3. Step 3: Cross multiply
    918.60x = 1,373.90 × 821.80
  4. Step 4: Simplify right side
    918.60x = 1,129,071.02
  5. Step 5: Solve for x
    x = 1,129,071.02/918.60
  6. Step 6: Final answer
    x = 1,229.12

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.