Statistics Test

Result

Statistics Test - 5

Score
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out of -
Rank
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TIME Taken - -

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Weekly Quiz Competition

Question 1
1 / -0

The mean weight of 150 students in 6^th class is 60 kg. The mean weight of boys in the class is 70 kg and that of girls is 55 kg. The number of boys and girls in the class are respectively

A
50, 100

B
70, 80

C
40, 110

D
None of these

Solution

Let total number of boys = x
Let total number of girls = y
A. T. Q.;
x + y = 150 ... (i)
and
70x + 55y = 60x + 60y
10x = 5y
y = 2x ... (ii)
Putting the value of y in equation (i),
we get
x = 50 and y = 100
Question 2
1 / -0

The average marks scored by 30 students in a test are 78. The marks of student A were marked 62 instead of 78, and the marks of student B were marked 98 instead of 55. Find the correct average of marks scored by the 30 students.

A
78.9

B
77.1

C
76.1

D
75.9

Solution

Average marks scored by the students = 78
Total marks scored by 30 students = 78 x 30
= 2340

Now, we know that there was a mistake while marking the marks.

Therefore, correct total marks scored by 30 students = 2340 + (78 - 62) + (55 - 98)
= 2340 + 16 – 43
= 2313

Correct average = 2313 ÷ 30 = 77.1
Question 3
1 / -0

The average marks scored by Harpreet and Gurpreet in three tests are 57 and 61, respectively. If the ratio of the marks scored by them in English is 7 : 9, find the average marks of Gurpreet in the other two tests, given that the average marks scored by Harpreet in the other two subjects were 54.

A
24

B
48

C
51

D
144

Solution

Total marks scored by Harpreet in all tests = 57 × 3 = 171
Total marks scored by Harpreet in the two tests (other than English) = 54 × 2 = 108

Marks scored by Harpreet in English = 171 – 108 = 63
Marks scored by Gurpreet in English = 9/7 × 63 = 81

Total marks scored by Gurpreet in all tests = 61 × 3 = 183
Total marks scored by Gurpreet in the two tests (other than English) = 183 - 81 = 102

Required average = 102 ÷ 2 = 51