Stav is studying the large data set for September 2015 He codes the variable Daily Mean Pressure, x, using the formula y = x – 1010 The data for all 30 days from Hurn are summarised by ∑y = 214 ∑x² = 5912 (a) State the units of the variable x (b) Find the mean Daily Mean Pressure for these 30 days - Edexcel - A-Level Maths Statistics - Question 3 - 2021 - Paper 1

To find the mean Daily Mean Pressure for the 30 days, use the formula:

ar{x} = rac{∑y}{n} + 1010

where

• $∑y = 214$
• $n = 30$.

Calculating: ar{x} = rac{214}{30} + 1010 = 7.1333 + 1010 = 1017.1333

Thus, the mean Daily Mean Pressure is approximately 1017 hPa.

To find the standard deviation, apply the formula:

ootsum{∑x^2}{n} - ar{x}^2}{n}$$ Calculating: $$ ext{Standard Deviation} = rac{ ootsum{5912}{30} - (1017.1333)^2}{30}$$ This simplifies to: $$ ext{Standard Deviation} ext{approx. } = 12.0905.$$

Given that high pressure areas cause winds to circulate in a clockwise direction:

• Leuchars (highest pressure) is clockwise from Hurn, placing it first.
• Hurn follows as the middle location with lower pressure.
• Heathrow is last as it is in an anticlockwise direction from Hurn.

Correct placement:

• Heathrow: W
• Hurn: N
• Leuchars: E.