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Finding the Fourth Proportional to 2.89, 4 and 2.78

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Solution

The fourth proportional to 2.89, 4 and 2.78 is: 3.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    2.89 : 4 = 2.78 : x
  2. Step 2: Convert to fraction form
    2.89/4 = 2.78/x
  3. Step 3: Cross multiply
    2.89x = 4 × 2.78
  4. Step 4: Simplify right side
    2.89x = 11.12
  5. Step 5: Solve for x
    x = 11.12/2.89
  6. Step 6: Final answer
    x = 3.85

Related Problems

Find fourth proportional to 1.45, 2 and 1.39
Half scale
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Double scale
Find fourth proportional to 3.89, 5.38 and 3.78
Similar ratio
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1.5x scale

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.