Skip to content
Question of 90
Q.

Find the mean deviation about the median for the following data:

Marks0-1010-2020-3030-4040-5050-60
Frequency68141642

OR

Find the standard deviation for the following data:

| xix_i | 3 | 8 | 13 | 18 | 23 |

|---|---|---|---|---|

| fif_i | 7 | 10 | 15 | 10 | 6 |

Madhya Pradesh MpbseMP Board Higher Secondary (Class 11) 2024Subjective· 4mImportance★★★★★
0% · 0/90 Questions
🔒 Locked · start free trial →

You're viewing a preview — the full solution, concept, methods & PYQ mapping are locked.

Start your 14-day free trial to unlock the full solution →

With N=50N=50, the median class is 2020–3030 (median ≈27.86\approx 27.86); the mean deviation about the median works out to ≈10.34\approx 10.34.

Given classes 00-10,…,5010,\ldots,50-6060 with frequencies 6,8,14,16,4,26,8,14,16,4,2.

Step 1 — find N and midpoints: N=6+8+14+16+4+2=50N = 6+8+14+16+4+2 = 50. Midpoints: 5,15,25,35,45,555,15,25,35,45,55.

Step 2 — locate the median class: Cumulative frequencies: 6,14,28,44,48,506,14,28,44,48,50. N/2=25N/2 = 25. The class where cumulative frequency first reaches/exceeds 25 is 2020-3030 (cf =28=28), so this is the median class, with l=20l=20, cf (before) =14=14, f=14f=14, h=10h=10.

Step 3 — compute the median: Median=l+N2−cff×h=20+25−1414×10=20+11014≈27.86\text{Median} = l + \dfrac{\frac{N}{2}-cf}{f}\times h = 20 + \dfrac{25-14}{14}\times 10 = 20 + \dfrac{110}{14} \approx 27.86.

Step 4 — mean deviation about median: For each midpoint xix_i, compute ∣xi−27.86∣|x_i - 27.86|, multiply by fif_i, and sum:

xix_i51525354555
∣xi−27.86∣\lvert x_i-27.86\rvert22.8612.862.867.1417.1427.14
fi∣xi−27.86∣f_i\lvert x_i-27.86\rvert137.14102.8640.00114.2968.5754.29

Step 5. Sum Σfi∣xi−Median∣≈517.14\Sigma f_i|x_i-\text{Median}| \approx 517.14. Mean deviation =517.1450≈10.34= \dfrac{517.14}{50} \approx 10.34.

…

Unlock everything free for 14 days

  • Full step-by-step solutions
  • Concept-first explanations
  • Methods, shortcuts & mistakes
  • PYQ mapping + timed mock tests

Full access for 14 days. No credit card required.