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Finding the Fourth Proportional to 841.20, 1,261.80 and 780.45

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Solution

The fourth proportional to 841.20, 1,261.80 and 780.45 is: 1,170.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    841.20 : 1,261.80 = 780.45 : x
  2. Step 2: Convert to fraction form
    841.20/1,261.80 = 780.45/x
  3. Step 3: Cross multiply
    841.20x = 1,261.80 × 780.45
  4. Step 4: Simplify right side
    841.20x = 984,771.81
  5. Step 5: Solve for x
    x = 984,771.81/841.20
  6. Step 6: Final answer
    x = 1,170.68

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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.