The mean of set of 30 observations is 75. If each observation is multiplied by a non-zero number $$\lambda $$ and then each of them is decreased by 25, their mean remains the same. Then $$\lambda $$ is equal to :
- A$${1 \over 3}$$
- B$${2 \over 3}$$
- C$${4 \over 3}$$
- D$${10 \over 3}$$
✓ Correct answer: C
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