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Finding the Fourth Proportional to 804.80, 1,205.40 and 642.80

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Solution

The fourth proportional to 804.80, 1,205.40 and 642.80 is: 962.76

Step by Step Solution

  1. Step 1: Write the proportion equation
    804.80 : 1,205.40 = 642.80 : x
  2. Step 2: Convert to fraction form
    804.80/1,205.40 = 642.80/x
  3. Step 3: Cross multiply
    804.80x = 1,205.40 × 642.80
  4. Step 4: Simplify right side
    804.80x = 774,831.12
  5. Step 5: Solve for x
    x = 774,831.12/804.80
  6. Step 6: Final answer
    x = 962.76

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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.