please explain me 2 ques (1)the mean weight of a class of 20 students is 48kg.two more students weighing 60kg and 58 kg respectively join the class.what is the mean weight of the class now?? (2)the mean attendance of a school for the first four days of the week was 780 and for the first five days it was 840.how many were present on friday?? please tell me this today......

(1) We know that,

It is given that; the mean weight of a class 20 students is 48 kg. Let total weight of 20 student is *x* kg.

So,

…… (1)

Now, two more students weighing 60 kg and 58 kg respectively join the class. So, total number of student is 22.

Substitute value of x from equation (1), we have,

Hence mean weight of the class is 49 kg.

(2) The number of students present on the first 4 days

And, the number of students present on the first 5 days

So, number of students present on fifth day (Friday) =

(The number of students present on the first 5 days) – (the number of students present on the first 4 days)

Number of students present on fifth day = 4200-3120 =1080

Hence 1080 student were present on Friday

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