iTM Computers Sdn. Bhd. employs production staff to assemble thousands o computers daily. Samples of the work of 10 production staff are shown in the following able. One hundred units of computers that were assembled by these staff were carefully examined and the errors found were counted. The fraction defective of each ample was then computed. Staff 2 3 4 5 6 7 8 9 10 Numbers Fraction Defective (p) 0.06 0.05 0.04 0.02 0.04 0.03 0.05 0.04 0.04 0.0 Based on the historical data, calculate the control limit at a 90% confidence interva (Z score is 1.64)