4. The average life of a breadvinaking maehine is 7.5 years with a standard deviation of 1.23 years. Assuming that the lives of these machines follow a normal distribution, nd the value of If: to the left of which 2T% of the means computed from random samples of size 5} would fell. Please use proper notation and show clearly the strmderdizationfdestandardization. [You may use R here, if you wish so, but you must show all the steps of the solution and use proper notation.) (10 points)