How can I solve this?

If each value in the data set is multiplied by a constant value, the mean, median, mode, range, and standard deviation will all be scaled by the same amount.

Therefore, if each value in the data set is multiplied by 0.5:

Mean: 320 × 0.5 = 160
Median: 300 × 0.5 = 150
Mode: none × 0.5 = none
Range: 210 × 0.5 = 105
Standard deviation: 70.6 × 0.5 = 35.3

Proof

Data set: {1, 2, 3, 4, 5}

[tex]\sf Mean\:\mu =\dfrac{\sum x_i}{n}= \dfrac{1+2+3+4+5}{5} = 3[/tex]

[tex]\sf Median = 3[/tex]

[tex]\sf Mode = none[/tex]

[tex]\sf Range = 5-1=4[/tex]

[tex]\sf Standard\:deviation\:\sigma=\sqrt{\dfrac{\sum (x_i-\mu)^2}{n}}=\sqrt{\dfrac{10}{5}}=\sqrt{2}[/tex]

If we multiply each value by 0.5, the new data set is:

{0.5, 1, 1.5, 2, 2.5}

[tex]\sf Mean\:\mu =\dfrac{\sum x_i}{n}= \dfrac{0.5+1+1.5+2+2.5}{5} = 1.5[/tex]

[tex]\sf Median = 1.5[/tex]

[tex]\sf Mode = none[/tex]

[tex]\sf Range = 2.5-0.5=2[/tex]

[tex]\sf Standard\:deviation\:\sigma=\sqrt{\dfrac{\sum (x_i-\mu)^2}{n}}=\sqrt{\dfrac{2.5}{5}}=\dfrac{\sqrt{2}}{2}[/tex]

Therefore, if each value in the data set is multiplied by 0.5, the mean, median, mode, range, and standard deviation are all scaled by the same amount.