The burning rates of two different solid-fuel propellants used in aircrew escape systems are being studied. It is known that both propellants have the same standard deviation of burning rate; σ1 = σ2 = 3 centimetres per second. Two random samples of n1 = n2 = 20 are tested; the sample mean burning rates are 23.7 and 24 centimetres per second respectively. If you want to test the hypothesis that the burning rates of the 2 propellants are different, what is the value of zcalc? In computing zcalc, use the hypothesis test with respect to LaTeX: \mu1-\mu2 μ 1 − μ 2 . Please report your answer in 2 decimal places.