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1) The Standard deviation of the set A= {1, 2, 3, 4, 5} remains the same after the inclusion of a new value x in the set 2) The Mean of set {1, 2, 3, 4, 5} remains the same after the inclusion of a new value x in the set
target find value of x 1) The Standard deviation of the set A= {1, 2, 3, 4, 5} remains the same after the inclusion of a new value x in the set
SD is the avg variation of terms from the mean value here SD is >1 and will not change if the new inclusion of value of x is 3 sufficient #2 The Mean of set {1, 2, 3, 4, 5} remains the same after the inclusion of a new value x in the set current mean of set = 3 with addition of 3 the mean will be 3 only sufficient
OPTION D is correct
GMATinsight
find the value of x?
1) The Standard deviation of the set A= {1, 2, 3, 4, 5} remains the same after the inclusion of a new value x in the set 2) The Mean of set {1, 2, 3, 4, 5} remains the same after the inclusion of a new value x in the set
St1: if we use x = 3 in St1, the SD will decrease.
Please recheck.
GMATinsight
find the value of x?
1) The Standard deviation of the set A= {1, 2, 3, 4, 5} remains the same after the inclusion of a new value x in the set 2) The Mean of set {1, 2, 3, 4, 5} remains the same after the inclusion of a new value x in the set
1) The Standard deviation of the set A= {1, 2, 3, 4, 5} remains the same after the inclusion of a new value x in the set 2) The Mean of set {1, 2, 3, 4, 5} remains the same after the inclusion of a new value x in the set
From (1), x can be \(\frac{15 + 2\sqrt{15}}{5}\) or \(\frac{15 + 2\sqrt{15}}{5}\), so we cannot determine a single value of x. Not sufficient.
Adding x = 3 to A = {1, 2, 3, 4, 5}, which has a standard deviation of \(\sqrt{2}\), produces {1, 2, 3, 3, 4, 5}, which has a standard deviation of \(\sqrt{\frac{5}{3}}≈1.2910\). Adding an element equal to the mean reduces the standard deviation (as long as the set has more than one non-identical element).
From (2), x = 3, and (2) is sufficient.
So (1) and (2) contradict each other, which never occurs in a proper GMAT DS question.
Ignore this question.
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