Home / 136.80-188.70-85

Finding the Fourth Proportional to 136.80, 188.70 and 85

Calculator

Solution

The fourth proportional to 136.80, 188.70 and 85 is: 117.25

Step by Step Solution

  1. Step 1: Write the proportion equation
    136.80 : 188.70 = 85 : x
  2. Step 2: Convert to fraction form
    136.80/188.70 = 85/x
  3. Step 3: Cross multiply
    136.80x = 188.70 × 85
  4. Step 4: Simplify right side
    136.80x = 16,039.50
  5. Step 5: Solve for x
    x = 16,039.50/136.80
  6. Step 6: Final answer
    x = 117.25

Related Problems

Find fourth proportional to 68.40, 94.35 and 42.50
Half scale
Find fourth proportional to 273.60, 377.40 and 170
Double scale
Find fourth proportional to 137.80, 190.08 and 86
Similar ratio
Find fourth proportional to 205.20, 283.05 and 127.50
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.