A mean is an arithmetic average of a set of observations. The higher mean score out of two grades will be of grade 6.
What is Mean?
A mean is an arithmetic average of a set of observations. it is given by the formula,
[tex]\rm Mean=\dfrac{\text{Sum of all obervation}}{\text{Number of observation}}[/tex]
The mean of the 6th grade will be,
[tex]\rm Mean_1 = \dfrac{(70 \times 6)+(80 \times 4)+(90 \times 6)+(100 \times 4)}{20} = \dfrac{1680}{20} = 84[/tex]
The mean of the 7th grade will be,
[tex]\rm Mean_2 = \dfrac{(50 \times 5)+(60 \times 7)+(70 \times 4)+(80 \times 4)}{20} = \dfrac{1270}{20} = 63.5[/tex]
Hence, the higher mean score out of two grades will be of grade 6.
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