# Mean, median & grouped summaries

Code With Purpose · Hinglish · Free starter lesson

## Concept

Mean ke liye sab values jodo aur count se divide karo. Median sorted data ki middle value hai; even count mein beech ki do values ka average hai. Bahut badi ya chhoti values mean ko median se zyada move kar sakti hain.

Group-wise summary differences dikhati hai jo overall average mein chhup sakte hain. Sample size bhi batao: do observations ka average aur do hazaar ka average ek jaisa evidence nahi dete. Pandas ki kai aggregations missing values ko skip karti hain, toh zarurat par missing count bhi report karo.

Pattern dekhne se cause prove nahi hota. Study time aur marks ka relation prior preparation ya dusre factors se bhi ho sakta hai. Yeh chhota sample calculations practice karne ke liye hai, learners par claim karne ke liye nahi. Code standard library se chalega.

## Example

```python
from statistics import mean, median
hours = [1, 2, 2, 3, 12]
print(f"Mean: {mean(hours):.1f}")
print(f"Median: {median(hours):.1f}")
print(f"Count: {len(hours)}")
```

## Expected output

```text
Mean: 4.0
Median: 2.0
Count: 5
```

## Exercise

12 hatane ke baad mean aur median nikalo. Kya change hua explain karo, lekin extreme value ko automatically error mat samjho.

## Suggested solution

```
from statistics import mean, median
hours = [1, 2, 2, 3]
print(mean(hours))    # 2
print(median(hours))  # 2.0
# The mean falls; the median stays the same.
# Investigate whether 12 is valid before deciding to exclude it.
```

## Takeaway

Context, sample size aur ek se zyada summary saath mein batao.

Reference: https://docs.python.org/3/library/statistics.html

https://codewithpurposeai.in/lesson-data-summary.html?lang=hinglish