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प्रश्न
The mean of 5 numbers is 27. If one new number is included, the new mean is 25. Find the included number.
उत्तर
Mean of 5 observations = 27
Total sum of 5 observations = 27 × 5 = 135
New mean with 6 numbers
When the new number is included, the mean becomes 25, and the total numbers increase to 6.
On including an observation, the mean of 6 observation = 25 × 6 = 150
⇒ Included observations = Total Mean of 6 observations – Total mean of 5 observations
= 150 − 135 = 15
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संबंधित प्रश्न
Attempt this question on graph paper.
| Age (yrs ) | 5-15 | 15-25 | 25-35 | 35-45 | 45-55 | 55-65 | 65-75 |
| No.of casualties | 6 | 10 | 15 | 13 | 24 | 8 | 7 |
(1) Construct the 'less than' Cumulative frequency curve for the above data. using 2 cm =10 years on one axis and 2 cm =10 casualties on the other.
(2)From your graph determine :
(a)the median
(b)the lower quartile
Find the arithmetic mean (correct to the nearest whole number) by using step-deviation method.
| x | 5 | 10 | 15 | 20 | 25 | 30 | 35 | 40 | 45 | 50 |
| f | 20 | 43 | 75 | 67 | 72 | 45 | 39 | 9 | 8 | 6 |
Find the mean of the following frequency distribution by the step deviation method :
| Class | 0-20 | 20-40 | 40-60 | 60-80 | 80-100 | 100-120 | 120-140 |
| Frequency | 12 | 24 | 52 | 88 | 66 | 42 | 16 |
Find the median of the following:
11, 8, 15, 5, 9, 4, 19, 6, 18
Estimate the median, the lower quartile and the upper quartile of the following frequency distribution by drawing an ogive:
| Age( in yrs) | Under 10 | Under 20 | Under 30 | Under 40 | Under 50 | Under 60 |
| No. of males | 6 | 10 | 25 | 32 | 43 | 50 |
Find the mean of all factors of 10.
The mean of a certain number of observations is 32. Find the resulting mean, if the observation is, multiplied by 2
The mean of a certain number of observations is 32. Find the resulting mean, if the observation is decreased by 20%.
If the mean of x, x + 2, x + 4, x + 6 and x + 8 is 13, find the value of x. Sum of data.
The median of the following observations arranged in ascending order is 64. Find the value of x:
27, 31, 46, 52, x, x + 4, 71, 79, 85, 90
