Home / 70.31-105.47-31.78

Finding the Fourth Proportional to 70.31, 105.47 and 31.78

Calculator

Solution

The fourth proportional to 70.31, 105.47 and 31.78 is: 47.67

Step by Step Solution

  1. Step 1: Write the proportion equation
    70.31 : 105.47 = 31.78 : x
  2. Step 2: Convert to fraction form
    70.31/105.47 = 31.78/x
  3. Step 3: Cross multiply
    70.31x = 105.47 × 31.78
  4. Step 4: Simplify right side
    70.31x = 3,351.84
  5. Step 5: Solve for x
    x = 3,351.84/70.31
  6. Step 6: Final answer
    x = 47.67

Related Problems

Find fourth proportional to 35.16, 52.74 and 15.89
Half scale
Find fourth proportional to 140.62, 210.94 and 63.56
Double scale
Find fourth proportional to 71.31, 106.97 and 32.78
Similar ratio
Find fourth proportional to 105.47, 158.21 and 47.67
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.