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Finding the Fourth Proportional to 830.80, 1,243.64 and 811.60

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Solution

The fourth proportional to 830.80, 1,243.64 and 811.60 is: 1,214.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    830.80 : 1,243.64 = 811.60 : x
  2. Step 2: Convert to fraction form
    830.80/1,243.64 = 811.60/x
  3. Step 3: Cross multiply
    830.80x = 1,243.64 × 811.60
  4. Step 4: Simplify right side
    830.80x = 1,009,338.22
  5. Step 5: Solve for x
    x = 1,009,338.22/830.80
  6. Step 6: Final answer
    x = 1,214.90

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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.