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Finding the Fourth Proportional to 858.70, 1,290.94 and 678.28

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Solution

The fourth proportional to 858.70, 1,290.94 and 678.28 is: 1,019.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    858.70 : 1,290.94 = 678.28 : x
  2. Step 2: Convert to fraction form
    858.70/1,290.94 = 678.28/x
  3. Step 3: Cross multiply
    858.70x = 1,290.94 × 678.28
  4. Step 4: Simplify right side
    858.70x = 875,618.78
  5. Step 5: Solve for x
    x = 875,618.78/858.70
  6. Step 6: Final answer
    x = 1,019.70

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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.