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Finding the Fourth Proportional to 690.70, 1,036.06 and 257.78

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Solution

The fourth proportional to 690.70, 1,036.06 and 257.78 is: 386.67

Step by Step Solution

  1. Step 1: Write the proportion equation
    690.70 : 1,036.06 = 257.78 : x
  2. Step 2: Convert to fraction form
    690.70/1,036.06 = 257.78/x
  3. Step 3: Cross multiply
    690.70x = 1,036.06 × 257.78
  4. Step 4: Simplify right side
    690.70x = 267,075.55
  5. Step 5: Solve for x
    x = 267,075.55/690.70
  6. Step 6: Final answer
    x = 386.67

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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.