quant-1

[wanderwanderer]

7.51 8.22 7.86 8.36
8.09 7.83 8.30 8.01
7.73 8.25 7.96 8.53

Coffee vending machine is designed to pour 8 ounces of coffee into a cup. Data for 1000 cups have been collected and 12 of them have been selected as shown above. If the mean is 8.1 and the standard deviation is 0.3 , how many of them are within a standard deviation of 1.5?
coffee vending answer : 4 , 6 , 9, 10, 11 .. answer :11

Pls explain..

[sonikamadala]

IMO answer is 11.

M =8.1
SD = 0.3
1.5(SD) = 0.45

Stem is asking us to find the no.of values falls within the range of standard deviation of 1.5.
So we have to consider both left side and right side of the mean.

left side of the mean starts at =8.1- 1.5(SD) = 7.65
right side of the mean ends at =8.1+ 1.5(SD) = 8.55

i.e 7.65 <value <8.55.

except 7.51, all the values falls under above range.

so answer is 11.

[india_chintan]

agree wid u sonika. gud explanation.