Comparing bulb lifespans from back-to-back stems

Comparing bulb lifespans from back-to-back stems

Secondary 2
TGM Original Questions

Factory A lifespans (h): 320,330,330,340,350,350,360,370,380,390,410,420,430,440,450,460,470,480,500,520. Factory B: 340,350,360,370,380,390,410,430,450,450,450,470,490,510,530,550,570,590,610,630.

  1. Draw a back-to-back stem-and-leaf diagram using hundreds as stems and tens as leaves.
  2. Find the overall mode.
  3. Factory-A bulbs at or below 360 h fail; find the failure percentage.
  4. Find the probability a Factory-B bulb lasts below 470 h.
  5. Which factory lasts longer? Explain.

Solution:

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Answer:(i) correct back-to-back diagram; (ii) \(450\) h; (iii) \(35\%\); (iv) \(11/20\); (v) Factory B, with higher median \(450\) h versus \(400\) h.

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