Answer: 25
Step-by-step explanation:
Since, Total creepy-crawly creatures = 20
Out of which 80% are flies and 20% are spiders,
Thus, the total flies = 80% of 20 = 16
And, The total spiders = 20% of 20 = 4
Also, we know that the number of legs of a spider = 8,
⇒ Total legs belong to spiders out of 20 creepy-crawly creatures = 4×8 = 32
Again, the number of legs of a fly = 6
Thus, the total legs belong to flies out of 20 creepy-crawly creatures = 6×16 = 96
Hence, Total legs = 32 + 96 = 128
Answer:
a. 0.38%
b. 266.75 days
Step-by-step explanation:
We have the following data, mean (m) 269 and standard deviation (sd) 15, therefore:
a. The first thing is to calculate the number z:
z (x) = (x - m) / sd
z (309) = (309-269) / 15 = 2.67
When looking in the normal distribution table (attached), we have that at this value of z, the probability is:
P (z> 2.67), that is to say we must look in the table -2.67 and this value corresponds to 0.0038, that is to say 0.38%
b. Find the z-value with a left tail of 44%, i.e. 0.44. We look in the table for this value and what value of z corresponds.
invNorm (0.44) = -0.15
Find the corresponding number of days:
x = z * sd + m
we replace
d = -0.15 * 15 + 269 = 266.75 days
