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09 Feb 2026, 20:00
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A
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61% (01:01) correct
39%
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During an experiment, some grain was removed from each of the 10 sacks. If the standard deviation of the quantity of grain in the 10 sacks before the experiment was 5 pounds, what was the standard deviation of the same after the experiment?
(1) From each sack, 20% grain was removed.
(2) The total quantity of grain in 10 sacks was 200 pounds before the experiment and 160 pounds after the experiment.
(1) From each sack, 20% grain was removed.
(2) The total quantity of grain in 10 sacks was 200 pounds before the experiment and 160 pounds after the experiment.
09 Feb 2026, 23:53
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SD property to remember - SD is multiplied by the constant if each dataset is multiplied by same constant. SD doesn't change if same constant added/subtracted from each dataset.
Statement 1: Each data set gets multiplied by 0.8. Thus SD also gets multiplied by 0.8. i.e SD(new) = 5x0.8=4. Sufficient.
Statement 2: We know the total grain reduction of 40pounds in 10 sacks. But we don't know how much from each sack was reduced - we can have different values for that arrangement. Not sufficient.
Statement 1: Each data set gets multiplied by 0.8. Thus SD also gets multiplied by 0.8. i.e SD(new) = 5x0.8=4. Sufficient.
Statement 2: We know the total grain reduction of 40pounds in 10 sacks. But we don't know how much from each sack was reduced - we can have different values for that arrangement. Not sufficient.
ExpertsGlobal5
10 Feb 2026, 00:24
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ExpertsGlobal5
Given that the standard deviation of the sack was 5 pounds before the start of experiment.
Some grains is removed from the 10 sacks, we need to find the new standard deviation.
When we remove or add something to a set of variables, the mean decreases or increases by the same value.
If, that’s the case the standard deviation which focuses on the gap doesn’t change.
So the standard deviation remains the same during addition or subtraction uniform across the set.
But, the same is not applicable to multiplication and division, it expands or contracts depending upon the operator.
Statement 1:
From each sack, 20% grain was removed.
If 20% is removed, we are left with 80% only.
So, each sack is not holding the same amount. Moreover, 80% of total. Is like multiplying 80% towards the mean and standard deviation. This multiplication factor is going to pull the S.D down.
New S.D = 80%*5 = 4 pounds.
Hence, Sufficient
(2) The total quantity of grain in 10 sacks was 200 pounds before the experiment and 160 pounds after the experiment.
With the total quantity and averages per sack is also clear. But, we speak of S.D which is the distance these values are spaced with respect to mean values.
If, these distances are not known, we cannot say anything conclusive about the standard deviation.
Hence, Insufficient
Option A
