Suppose a random sample of 137 households in a city was selected to determine the average annual household spending on food at home for city residents. Annual At Home Food Expenditures ($) 3487.13 3124.31 3129.13 2835.02 3147.72 3528.72 3372.89 3450.25 3354.95 3767.96 2732.22 3587.66 3552.52 3098.39 3193.42 2755.74 3417.89 3197.78 3303.27 3141.17 3522.02 3098.47 2753.28 3012.41 3358.82 3107.73 3427.31 2785.48 3108.74 3307.68 3404.19 3047.55 3384.74 3154.26 3233.28 3186.58 2896.31 3512.15 3164.51 3114.83 3590.75 2814.75 2863.44 3000.77 3121.07 3354.16 3024.98 3776.19 3252.95 3150.45 3400.98 3613.23 3246.43 3088.44 2936.89 2871.53 3161.05 3319.27 3261.69 2988.99 3394.87 3372.45 3661.98 3048.35 3140.03 2857.75 3319.01 3133.26 3213.67 3518.32 3414.55 3716.09 3751.01 2937.77 3538.43 3362.33 3669.83 3387.33 3167.13 3443.22 2989.34 3932.91 3487.39 3288.54 2865.96 3262.78 3057.06 3341.03 3637.36 3347.21 3133.19 3772.07 3304.97 2775.79 3306.33 3294.52 3113.84 3876.15 3453.55 3538.07 3053.51 3030.46 3165.81 3668.47 3348.82 3441.57 3140.47 3371.71 3577.32 3259.38 2959.21 3495.72 3483.29 3010.61 2806.95 2988.06 3660.36 3566.82 3449.18 3309.51 3425.72 2980.23 3141.94 3603.24 3322.66 3534.37 2990.22 3660.14 3249.31 2790.26 3138.18 3145.45 3263.12 3460.64 3351.59 3265.35 3260.71 Using the sample standard deviation as an estimate for the population standard deviation, calculate the sample size required to estimate the true population mean to within plus or minus20 with 95% confidence. How many additional samples must be taken? The required sample size is
