Aptitude Discussion

Q. |
The mean salary in ICM ltd. was Rs 1500, and the standard deviation was Rs 400. A year later each employee got a Rs 100 raise. After another year each employee's salary (including the above mentioned raise) was increased by $20%$. The standard deviation of the current salary is: |

✖ A. |
460 |

✔ B. |
480 |

✖ C. |
560 |

✖ D. |
none of these |

**Solution:**

Option(**B**) is correct

Mean salary was Rs 1500

Standard deviation = Rs 400

After 1 year all the employees got a uniform rise of Rs 100.

So, there will be no change in standard deviation.

After another year, every employee's salary was increased by $20\%$.

So, standard deviation will be increased by $20\%$.

Standard deviation

\(=480\times \dfrac{120}{100}\)

= Rs **480**