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Finding the Fourth Proportional to 2,158.40, 3,240 and 860.78

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Solution

The fourth proportional to 2,158.40, 3,240 and 860.78 is: 1,292.13

Step by Step Solution

  1. Step 1: Write the proportion equation
    2,158.40 : 3,240 = 860.78 : x
  2. Step 2: Convert to fraction form
    2,158.40/3,240 = 860.78/x
  3. Step 3: Cross multiply
    2,158.40x = 3,240 × 860.78
  4. Step 4: Simplify right side
    2,158.40x = 2,788,927.20
  5. Step 5: Solve for x
    x = 2,788,927.20/2,158.40
  6. Step 6: Final answer
    x = 1,292.13

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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.