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Finding the Fourth Proportional to 815.54, 1,220.01 and 678.80

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Solution

The fourth proportional to 815.54, 1,220.01 and 678.80 is: 1,015.45

Step by Step Solution

  1. Step 1: Write the proportion equation
    815.54 : 1,220.01 = 678.80 : x
  2. Step 2: Convert to fraction form
    815.54/1,220.01 = 678.80/x
  3. Step 3: Cross multiply
    815.54x = 1,220.01 × 678.80
  4. Step 4: Simplify right side
    815.54x = 828,142.79
  5. Step 5: Solve for x
    x = 828,142.79/815.54
  6. Step 6: Final answer
    x = 1,015.45

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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.