Question

Hello everyone please I need help with this question quickly!

The table shows some information about the lifetimes, t, in hours, of some lightbulbs.

Lifetime Frequency
25 < t ≤ 50 100
50 < t ≤ 100 45
100 < t ≤ 150 67
150 < t ≤ 200 50
200 < t ≤ 250 0
250 < t ≤ 300 12
300 < t ≤ 350 16

Estimate the mean lifetime of a bulb.
Give your answer rounded to 2 DP.

Answer 1

112.93

Step-by-step explanation:

`\sf \boxed{\sf Mean= (interval \ midpoint \ x \ frequency )/(Total \ Frequency) }`

Solving Stepwise:

`\rightarrow \sf (37.5 \ x \ 100 \ + \ 75 \ x \ 45 \ + \ 125 \ x \ 67 \ + \ 175 \ x \ 50 \ + \ 225 \ x \ 0 \ + \ 275 \ x \ 12 \ + \ 325 \ x \ 16 )/(100 + 45 +67+50+0+12+16)`

`\rightarrow \sf (32750)/(290)`

`\rightarrow \sf (3275)/(29)`

`\rightarrow \sf 112.9310345`

`\rightarrow \sf 112.93 \ (rounded \ to \ nearest \ 2 \ decimal \ places)`