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Finding the Fourth Proportional to 858.02, 1,287.30 and 780.80

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Solution

The fourth proportional to 858.02, 1,287.30 and 780.80 is: 1,171.45

Step by Step Solution

  1. Step 1: Write the proportion equation
    858.02 : 1,287.30 = 780.80 : x
  2. Step 2: Convert to fraction form
    858.02/1,287.30 = 780.80/x
  3. Step 3: Cross multiply
    858.02x = 1,287.30 × 780.80
  4. Step 4: Simplify right side
    858.02x = 1,005,123.84
  5. Step 5: Solve for x
    x = 1,005,123.84/858.02
  6. Step 6: Final answer
    x = 1,171.45

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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.