Three classes of continuous data are given as $0⩽x<4, 4⩽x<10$ and $10⩽x<18.$ The frequency densities of the classes $0⩽x<4$ and $10⩽x<18$ are in the ratio $4: 3$ and the total frequency of these two classes is $120.$ Find the least possible frequency of the modal class, given that the modal class is $4⩽x<10.$

Calculate the mean of the following sets of numbers: $28, 16, 83, 72, 105, 55, 6$ and $35$

Calculate the mean of the following sets of numbers:

$7.3, 8.6, 11.7, 9.1, 1.7$ and $4.2$

Calculate the mean of the following sets of numbers:

$3\frac{1}{2}, 5\frac{1}{4}, 9\frac{3}{4},-4\frac{1}{4}$ and $7\frac{3}{8}.$

Given that: $n=14$ and $\Sigma x=325.5,$ find $\overline{x}$

Given that: $n=45$ and $\overline{y}=23.6,$ find the value of $\Sigma y.$

Given that: $\Sigma z=4598$ and $\overline{z}=52.25,$ find the number of values in the set of data.