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Finding the Fourth Proportional to 780.10, 1,076.72 and 485.19

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Solution

The fourth proportional to 780.10, 1,076.72 and 485.19 is: 669.67

Step by Step Solution

  1. Step 1: Write the proportion equation
    780.10 : 1,076.72 = 485.19 : x
  2. Step 2: Convert to fraction form
    780.10/1,076.72 = 485.19/x
  3. Step 3: Cross multiply
    780.10x = 1,076.72 × 485.19
  4. Step 4: Simplify right side
    780.10x = 522,405.97
  5. Step 5: Solve for x
    x = 522,405.97/780.10
  6. Step 6: Final answer
    x = 669.67

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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.