In a school laboratory the air temperature T (in ∘C) must stay at least −2∘C but be lower than 6∘C.
a. (i) Write a linear inequality that represents the acceptable values of T.
b. (ii) The heater is controlled by a knob reading y so that T=0.5y−4. Form a linear inequality in y that guarantees the temperature requirement in part (i).
c. (iii) Solve the inequality obtained in part (ii).
d. (iv) Represent the admissible values of y on a number line with appropriate end-points and shading.