Home / 103.78-143.40-100

Finding the Fourth Proportional to 103.78, 143.40 and 100

Calculator

Solution

The fourth proportional to 103.78, 143.40 and 100 is: 138.18

Step by Step Solution

  1. Step 1: Write the proportion equation
    103.78 : 143.40 = 100 : x
  2. Step 2: Convert to fraction form
    103.78/143.40 = 100/x
  3. Step 3: Cross multiply
    103.78x = 143.40 × 100
  4. Step 4: Simplify right side
    103.78x = 14,340
  5. Step 5: Solve for x
    x = 14,340/103.78
  6. Step 6: Final answer
    x = 138.18

Related Problems

Find fourth proportional to 51.89, 71.70 and 50
Half scale
Find fourth proportional to 207.56, 286.80 and 200
Double scale
Find fourth proportional to 104.78, 144.78 and 101
Similar ratio
Find fourth proportional to 155.67, 215.10 and 150
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.