The maximum temperature of a city during summer follows normal distribution. On a particular day, the probability that the maximum temperature of the city is more than $31^{\circ}$ celsius is $0.3085 ,$ whereas the probability that during some other day, the maximum temperature is less than $27^{\circ}$ is $0.0668 .$ Find mean and standard deviation of the maximum temperature of the city.
Answer
$30$ Celsius and Standard deviation is $2$ Celsius.
The average monthly expense of students residing in university hostel is $₹ 2,000$ and its standard deviation is $₹ 500 .$ If the monthly expense of students follow normal distribution then $(1)$ Find percentage of students having expense between $₹ 750$ and $₹ 1,250.\ (2)$ Find percentage of students having expense less than $₹ 2,400$.