Back to back stem and leaf

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               Revision :-Back to Back Stem and Leaf (1)
             Two makes of light bulbs are being compared
                    to see which has the longest life.
Fourteen bulbs of each make are tested under laboratory conditions and
         the results for the tests are shown in the table below.
           The data shows the time in days which each bulb
                  lasts on continuous use of the bulb.

  Draw a back to back stem and leaf diagram to compare the figures.



         High Energy Bulb                   Special Filament Bulb.

    64 48 44 70 52 46 58                   49 45 62 66 56 42 34
    55 67 51 52 46 60 69                   33 66 52 41 45 37 71

                 Which of the two makes of bulb would
                     you say had the longest life?


                      Which type would you buy?
               Revision:-Back to Back Stem and Leaf (2)
           Trials are carried out on two new types of plant
                 feed to try to determine which is best.
           Some plants are given the plant feed ′Bestfeed′
                  while others are given ′Awardfeed′.
 After a while the heights of the plants are measured in centimeters.
              The results are shown in the tables below.

‘Bestfeed’ – growth in centimetres   ‘Awardfeed’ – growth in centimetres

  8.3   7.6   9.4   10.4    6.7        7.6     6.8    5.5   11.2    12.3
  7.8   7.8   7.9    8.4    8.2        7.8     7.5    7.6    6.9        6.8
  9.7   9.5   9.4    9.7    10.2       10.2   10.2    9.3    7.0        7.3



   Draw a back to back stem and leaf diagram to compare the figures.
                Which plant food do you think is best?
              Which one would you buy for your plants?
                  Revision:-Back to Back Stem and Leaf (3)
             Tests are to be carried out on a new type of turkey
                   food to see if the new food significantly
                      increases the weight of the turkeys.
             Fifteen turkeys are given the new food and another
                   fifteen are fed on the usual turkey food.
              The weight increases in the turkeys are recorded
over a short period of time and these results are shown in the tables below.
    Draw a back to back stem and leaf diagram to compare the figures.

         Weight increase ( in Kg)                   Weight increase ( in Kg)
               usual food                                  new food
       4.2   5.6    2.7    3.9      1.7         5.5      2.9   3.5   3.4   3.4
       2.8   3.1    5.3    4.2      3.6         3.8      2.4   2.5   3.9   1.8
       3.4   2.3    3.8    4.9      2.3         1.9      2.6   6.3   4.3   2.0


       The new food costs more than the usual food for the turkeys.
       Do the results justify changing to the new type of turkey food?
                                          I don’t like
                                          Christmas!

				
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