$4.$a$).$ A first order system requires $1$ minute to indicate $98$ percent of a unit step input response and subsequently remain in $-2\%$ error thereafter. what is the maximum frequency at which it will remain $5$ percent inaccurate?b$).$ The temperature of a greenhouse increases at the rate of $4$ oC per hour in summer. The thermometer used to measure the temperature must not be in error of more than $0\mathrm{.}2$ oC$.$ What must be the time constant of the thermometer?