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Finding the Fourth Proportional to 858.04, 1,288.80 and 643

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Solution

The fourth proportional to 858.04, 1,288.80 and 643 is: 965.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    858.04 : 1,288.80 = 643 : x
  2. Step 2: Convert to fraction form
    858.04/1,288.80 = 643/x
  3. Step 3: Cross multiply
    858.04x = 1,288.80 × 643
  4. Step 4: Simplify right side
    858.04x = 828,698.40
  5. Step 5: Solve for x
    x = 828,698.40/858.04
  6. Step 6: Final answer
    x = 965.80

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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.