Home / 109.21-163.61-78.70

Finding the Fourth Proportional to 109.21, 163.61 and 78.70

Calculator

Solution

The fourth proportional to 109.21, 163.61 and 78.70 is: 117.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    109.21 : 163.61 = 78.70 : x
  2. Step 2: Convert to fraction form
    109.21/163.61 = 78.70/x
  3. Step 3: Cross multiply
    109.21x = 163.61 × 78.70
  4. Step 4: Simplify right side
    109.21x = 12,875.60
  5. Step 5: Solve for x
    x = 12,875.60/109.21
  6. Step 6: Final answer
    x = 117.90

Related Problems

Find fourth proportional to 54.60, 81.80 and 39.35
Half scale
Find fourth proportional to 218.42, 327.22 and 157.40
Double scale
Find fourth proportional to 110.21, 165.11 and 79.70
Similar ratio
Find fourth proportional to 163.81, 245.41 and 118.05
1.5x scale

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.