title: R programming data set
body: <p>I loaded mtcars dataset in R program.I saw a question regarding that </p>
  
  <p>1) find the average of mpg (miles per gallon of all automatic tranmission cars</p>
  
  <p>That is you have to check am column in mt cars data set and you have two values 0 for manual tranmission and 1 for automatic transmission and you have to first filter values with 1 and later you need to get the corresponding values for mpg column and find the mean for that </p>
  
  <p>for reference data set of mtcar is listed below:</p>
  
  <pre><code>&gt; mtcars
                       mpg cyl  disp  hp drat    wt  qsec vs am gear carb
  Mazda RX4           21.0   6 160.0 110 3.90 2.620 16.46  0  1    4    4
  Mazda RX4 Wag       21.0   6 160.0 110 3.90 2.875 17.02  0  1    4    4
  Datsun 710          22.8   4 108.0  93 3.85 2.320 18.61  1  1    4    1
  Hornet 4 Drive      21.4   6 258.0 110 3.08 3.215 19.44  1  0    3    1
  Hornet Sportabout   18.7   8 360.0 175 3.15 3.440 17.02  0  0    3    2
  Valiant             18.1   6 225.0 105 2.76 3.460 20.22  1  0    3    1
  Duster 360          14.3   8 360.0 245 3.21 3.570 15.84  0  0    3    4
  Merc 240D           24.4   4 146.7  62 3.69 3.190 20.00  1  0    4    2
  Merc 230            22.8   4 140.8  95 3.92 3.150 22.90  1  0    4    2
  Merc 280            19.2   6 167.6 123 3.92 3.440 18.30  1  0    4    4
  Merc 280C           17.8   6 167.6 123 3.92 3.440 18.90  1  0    4    4
  Merc 450SE          16.4   8 275.8 180 3.07 4.070 17.40  0  0    3    3
  Merc 450SL          17.3   8 275.8 180 3.07 3.730 17.60  0  0    3    3
  Merc 450SLC         15.2   8 275.8 180 3.07 3.780 18.00  0  0    3    3
  Cadillac Fleetwood  10.4   8 472.0 205 2.93 5.250 17.98  0  0    3    4
  Lincoln Continental 10.4   8 460.0 215 3.00 5.424 17.82  0  0    3    4
  Chrysler Imperial   14.7   8 440.0 230 3.23 5.345 17.42  0  0    3    4
  Fiat 128            32.4   4  78.7  66 4.08 2.200 19.47  1  1    4    1
  Honda Civic         30.4   4  75.7  52 4.93 1.615 18.52  1  1    4    2
  Toyota Corolla      33.9   4  71.1  65 4.22 1.835 19.90  1  1    4    1
  Toyota Corona       21.5   4 120.1  97 3.70 2.465 20.01  1  0    3    1
  Dodge Challenger    15.5   8 318.0 150 2.76 3.520 16.87  0  0    3    2
  AMC Javelin         15.2   8 304.0 150 3.15 3.435 17.30  0  0    3    2
  Camaro Z28          13.3   8 350.0 245 3.73 3.840 15.41  0  0    3    4
  Pontiac Firebird    19.2   8 400.0 175 3.08 3.845 17.05  0  0    3    2
  Fiat X1-9           27.3   4  79.0  66 4.08 1.935 18.90  1  1    4    1
  Porsche 914-2       26.0   4 120.3  91 4.43 2.140 16.70  0  1    5    2
  Lotus Europa        30.4   4  95.1 113 3.77 1.513 16.90  1  1    5    2
  Ford Pantera L      15.8   8 351.0 264 4.22 3.170 14.50  0  1    5    4
  Ferrari Dino        19.7   6 145.0 175 3.62 2.770 15.50  0  1    5    6
  Maserati Bora       15.0   8 301.0 335 3.54 3.570 14.60  0  1    5    8
  Volvo 142E          21.4   4 121.0 109 4.11 2.780 18.60  1  1    4    2
  </code></pre>
  
  <p>for any other help if needed go to search (near that plot interface where graph are visible) and type mtcars.</p>