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Finding the Fourth Proportional to 1,211.80, 1,817.80 and 390.06

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Solution

The fourth proportional to 1,211.80, 1,817.80 and 390.06 is: 585.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,211.80 : 1,817.80 = 390.06 : x
  2. Step 2: Convert to fraction form
    1,211.80/1,817.80 = 390.06/x
  3. Step 3: Cross multiply
    1,211.80x = 1,817.80 × 390.06
  4. Step 4: Simplify right side
    1,211.80x = 709,051.07
  5. Step 5: Solve for x
    x = 709,051.07/1,211.80
  6. Step 6: Final answer
    x = 585.12

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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.