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# Maths- Standard Deviation watch

1. Can someone help me with this question as I don't understand how to find the variance and standard deviation of multiple data sets/

Su and Ellen are collecting data on the durations of the eruptions of the volcano in their garden. Between them, they have recorded the duration of the last 60 eruptions.
-Su has timed 23 eruptions, with an average duration of 3.42 minutes and a standard deviation of 1.07 minutes.
-Ellen has timed 37 eruptions, with an average duration of 3.92 minutes and a standard deviation of 0.97 minutes.

Find the variance and standard deviation of the set of 60 durations.
2. (Original post by NehaRajput618)
Can someone help me with this question as I don't understand how to find the variance and standard deviation of multiple data sets/

Su and Ellen are collecting data on the durations of the eruptions of the volcano in their garden. Between them, they have recorded the duration of the last 60 eruptions.
-Su has timed 23 eruptions, with an average duration of 3.42 minutes and a standard deviation of 1.07 minutes.
-Ellen has timed 37 eruptions, with an average duration of 3.92 minutes and a standard deviation of 0.97 minutes.

Find the variance and standard deviation of the set of 60 durations.
-Su has timed 23 eruptions, with an average duration of 3.42 minutes and a standard deviation of 1.07 minutes.

Try writing out the formula for standard deviation and plug these numbers in. Please post all your working once you've done this and if you're not able to continue.
3. Thank you I worked it out now. I went wrong when plugging in the numbers into the formula before.
(Original post by Notnek)
-Su has timed 23 eruptions, with an average duration of 3.42 minutes and a standard deviation of 1.07 minutes.

Try writing out the formula for standard deviation and plug these numbers in. Please post all your working once you've done this and if you're not able to continue.

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