To find the rate of depreciation using "twice the straight line rate" for a car that depreciates fully in 4 years, let's work through the steps:

Step 1: Determine the Straight-Line Depreciation Rate

1. In the straight-line method, the depreciation rate is calculated by taking the reciprocal of the number of years over which the asset depreciates.
2. Since the car depreciates in 4 years, the straight-line depreciation rate is: $\text{Straight-line rate} = \frac{1}{4} = 0.25 \text{ or } 25\% \text{ per year}$

Step 2: Calculate Twice the Straight-Line Rate

Since the problem specifies "twice the straight line rate," we double the 25% rate: $\text{Twice the straight-line rate} = 2 \times 25\% = 50\%$

Answer:

The rate of depreciation, using twice the straight-line rate, is 50% per year.

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Here are some related questions you may find helpful:

1. What is the difference between straight-line depreciation and declining balance depreciation?
2. How is the residual value of an asset accounted for in depreciation calculations?
3. What is the impact of accelerated depreciation on a company’s financial statements?
4. How do other depreciation methods (like sum-of-the-years-digits) differ from the double-declining balance method?
5. How can one estimate the useful life of an asset for depreciation?

Tip: Depreciation methods impact tax and financial reporting differently; understanding them can optimize financial strategies.