Draw a diagram of a pulley system of velocity ratio 4. Calculate its mechanical advantage efficiency is 90%.

Explanation

### Step-by-Step Solution

#### Step 1: Draw the Diagram of the Pulley System
To illustrate a pulley system with a velocity ratio (VR) of 4, we can draw a simple diagram.

1. **Draw a Fixed Pulley**: Start by drawing a horizontal line to represent the fixed support.
2. **Add Four Pulleys**: Below the fixed support, draw four pulleys in a vertical arrangement. Each pulley should be connected by a rope.
3. **Indicate Load and Effort**:
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