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Q1. The height of a door opening is chosen to be equal to the 95th percentile height of a population. In a population of 20 million, calculate the number of people who will need to duck their head to avoid banging it on the doorway.
If the door opening height is equal to the 95th percentile height, then 5% of people will be taller than this height and will need to duck their heads. Calculate 5% of the 20 million population.
step 1: apply a formula & present the answer in SF
step 1: apply a formula & present the answer in SF
0.05 (5%) x 20 (assume data field of millions) = 1 Million
Q2. Figure 7.4 Prototype handheld controller and anthropometric data for a human hand
(a) Research indicates that distance A in Figure 7.4 should be 0.8 times the user's thumb length. Calculate distance A for the average man.
Step 1: Find the relevant data and convert
Step 1: Find the relevant data and convert
The 50th percentile value is the average value for the population. The table shows this as 51.0
Step 2: Apply the formula and present in SF
Step 2: Apply the formula and present in SF
From the anthropometric data, the average (50th percentile) man’s thumb length is 51.0 mm. Therefore:
Distance A = 0.8 (from the question) × 51 = 40.8mm
(b) The diameter of button B should be no smaller than half the user's thumb width. Calculate the minimum diameter of button B to make it suitable for 95% of women users.
step 1: Finding the data
step 1: Finding the data
Since we are looking for a minimum value for the diameter of button B, it is necessary to look at the largest users' thumbs. This is equivalent to the thumb width of the 95th percentile user. Users with smaller thumbs will find that the button is larger than half their thumb width, which is acceptable.
From the table data the 95th percentile women’s thumb width is 22.0 mm.
Step 2: Apply the formula and present in SF
Step 2: Apply the formula and present in SF
Minimum diameter of button B = 22 mm × 0.5 (half) = 11 mm
Q3 A man's height is 1910 mm. Using the anthropometric height data from the table below, explain how you know that more than 95% of the population are shorter than him.
step 1: explanation of the data
step 1: explanation of the data
From the anthropometric data, the 95th percentile height is 1860mm. 95% of the population will be shorter than this. Since the man’s height is greater than the 95th percentile, then more than 95% of the population will be shorter than him.
Q4. A bicycle designer wishes to produce a bike with an adjustable seat height. The ideal seat height is equal to the rider's hip height. The designer would like the seat adjustment range to suit 90% of female users.
(a) Use the anthropometric data in Figure 7.1 to determine the range over which the seat height needs to be adjustable for 90% of women users.
(b) Explain why this seat height range would result in the bike being unsuitable for more than half of the potential male users.
step 1: (a)
step 1: (a)
Adjustability over 90% of users corresponds to the range from the 5th percentile to the 95th percentile i.e. 90%. Using the women’s hip height from the anthropometric data:
Seat height range = 750mm (5%) to 890mm (95%)
step 2: (b)
step 2: (b)
Even at the highest setting of 890mm (95% of women), this height is less than the 50th percentile men’s hip height of 935 mm. Therefore, more than half the male users have a hip height higher than the highest seat setting and are, therefore, excluded.
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