I have 2 question which I'm stuck on. I get my and mixed up, I believe?

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**Q1:** The following table shows the number of take-away meals eaten by a random sample of students during a particular month.

Calculate an estimate of the mean and an estimate of the standard deviation of the numbers of take-away meals eaten by the population from which this sample was taken.

**My attempt:**

Mean:

Standard Deviation:

**The real answer:**

Mean: 10.7 (My Answer Correct)

Standard Deviation: 1.51 (My Answer Incorrect )

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**Q2:** Whig and Penn, solicitors, monitor the time spent on consultations with a random sample of 120 of their clients. The times, to the nearest minutes, are summarised in the following table.

Calculate estimates of the mean and variance of the population of times from which these data were obtained.

**My attempt:**

Mean:

Variance: This went terribally bad as I got a negative answer which is impossible.

**The real answer:**

Mean: 32.7 (My answer incorrect by 0.1 )

Variance: 162.03

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Please could someone help? Thank you in advance.