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Finding the Fourth Proportional to 1,200, 1,656 and 786.72

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Solution

The fourth proportional to 1,200, 1,656 and 786.72 is: 1,085.67

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,200 : 1,656 = 786.72 : x
  2. Step 2: Convert to fraction form
    1,200/1,656 = 786.72/x
  3. Step 3: Cross multiply
    1,200x = 1,656 × 786.72
  4. Step 4: Simplify right side
    1,200x = 1,302,808.32
  5. Step 5: Solve for x
    x = 1,302,808.32/1,200
  6. Step 6: Final answer
    x = 1,085.67

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.