# Find BDI and CDI from raw totals

Subject: Advertising and Public Relations

Exam: TEE

Reader: https://deep-learning-study-room.vercel.app/apr/#tee/practice/numbers/indices-counts

Canonical: https://deep-learning-study-room.vercel.app/read/apr/tee/practice/numbers--indices-counts/

Extra drills; no claim that these exact questions or allocated marks appeared in TEE

### Optional practice question. An area has 200,000 people out of a total population of 2,000,000. Brand sales are 30,000 units in the area and 200,000 units in all areas. Category sales are 120,000 units in the area and 600,000 units in all areas. Calculate BDI and CDI. [3 practice marks]

#### Answer

Authored illustration: these numbers were chosen to explain a faculty-note concept. No matching supplied-data question was found in the 14 recovered APR papers. Standalone calculation drills are optional practice; their marks are author-set.

## Given

| Quantity | Area | Total |
| --- | --- | --- |
| Population | 200,000 | 2,000,000 |
| Brand sales | 30,000 | 200,000 |
| Category sales | 120,000 | 600,000 |

## To find

BDI and CDI after converting counts to their proper percentage shares.

## Formula and why



$$
P_{\%}=\frac{P_a}{P_T}100,\ B_{\%}=\frac{B_a}{B_T}100,\ C_{\%}=\frac{C_a}{C_T}100
$$





$$
\text{BDI}=\frac{B_{\%}}{P_{\%}}100,\quad\text{CDI}=\frac{C_{\%}}{P_{\%}}100
$$



Each share must use its matching total. Do not divide area brand sales by total category sales to obtain the brand-sales share used in BDI.

## Step-by-step solution

#### Step 1. Find population share



$$
\frac{200000}{2000000}\times100=10\%
$$



#### Step 2. Find brand-sales share



$$
\frac{30000}{200000}\times100=15\%
$$



#### Step 3. Find category-sales share



$$
\frac{120000}{600000}\times100=20\%
$$



#### Step 4. Compute BDI



$$
\frac{15}{10}\times100=150
$$



#### Step 5. Compute CDI



$$
\frac{20}{10}\times100=200
$$



**Final answer:** BDI = 150; CDI = 200.

#### Practical interpretation · What the answer means

The area has a larger share of brand and category sales than its population share. Category concentration is stronger than brand concentration.