scores = [32, 35, 38, 40, 41, 43, 44, 45, 47, 48, 49, 50]
scores.sort()
n = len(scores)

def percentile(data, p):
    rank = (p / 100) * (n - 1)
    lower = int(rank)                      # index just below the rank
    upper = lower + 1 if lower + 1 < n else lower
    fraction = rank - lower
    return data[lower] + fraction * (data[upper] - data[lower])

p25 = percentile(scores, 25)
p50 = percentile(scores, 50)
p75 = percentile(scores, 75)
p90 = percentile(scores, 90)

print(f"25th percentile (Q1): {p25}")
print(f"50th percentile (median): {p50}")
print(f"75th percentile (Q3): {p75}")
print(f"90th percentile: {p90}")

# Output:
# 25th percentile (Q1): 39.5
# 50th percentile (median): 43.5
# 75th percentile (Q3): 47.25
# 90th percentile: 48.9