Home / 89.81-123.65-78.30

Finding the Fourth Proportional to 89.81, 123.65 and 78.30

Calculator

Solution

The fourth proportional to 89.81, 123.65 and 78.30 is: 107.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    89.81 : 123.65 = 78.30 : x
  2. Step 2: Convert to fraction form
    89.81/123.65 = 78.30/x
  3. Step 3: Cross multiply
    89.81x = 123.65 × 78.30
  4. Step 4: Simplify right side
    89.81x = 9,681.40
  5. Step 5: Solve for x
    x = 9,681.40/89.81
  6. Step 6: Final answer
    x = 107.80

Related Problems

Find fourth proportional to 44.90, 61.82 and 39.15
Half scale
Find fourth proportional to 179.61, 247.29 and 156.60
Double scale
Find fourth proportional to 90.81, 125.02 and 79.30
Similar ratio
Find fourth proportional to 134.71, 185.47 and 117.45
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.