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Finding the Fourth Proportional to 780.35, 1,170.53 and 643.11

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Solution

The fourth proportional to 780.35, 1,170.53 and 643.11 is: 964.67

Step by Step Solution

  1. Step 1: Write the proportion equation
    780.35 : 1,170.53 = 643.11 : x
  2. Step 2: Convert to fraction form
    780.35/1,170.53 = 643.11/x
  3. Step 3: Cross multiply
    780.35x = 1,170.53 × 643.11
  4. Step 4: Simplify right side
    780.35x = 752,776.33
  5. Step 5: Solve for x
    x = 752,776.33/780.35
  6. Step 6: Final answer
    x = 964.67

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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.