Answer:
A) 0.99413
B) 0.00022
Step-by-step explanation:
A) First of all let's find the total grading time from 6:50 P.M to 11:00 P.M.:
Total grading time; X = 11:00 - 6:50 = 4hours 10minutes = 250 minutes
Now since we are given an expected value of 5 minutes, the mean grading time for the whole population would be:
μ = n*μ_s ample = 42 × 5 = 210 minutes
While the standard deviation for the population would be:
σ = √nσ_sample = √(42 × 6) = 15.8745 minutes
To find the z-score, we will use the formula;
z = (x - μ)/σ
Thus;
z = (250 - 210)/15.8745
z = 2.52
From the z-distribution table attached, we have;
P(Z < 2.52) ≈ 0.99413
B) solving this is almost the same as in A above, the only difference is an additional 10 minutes to the time.
Thus, total time is now 250 + 10 = 260 minutes
Similar to the z-formula in A above, we have;
z = (260 - 210)/15.8745
z = 3.15
P(Z > 3.15) = 0.00022
Answer:
Step-by-step explanation:
a)
428721
Place of 2's 10s and 10,000s
Therefore its value is 20 and 20,000
Product of the place value = 20 x 20,000 = 4,00,000
b)
37,20,861
Place of 7 is 1,00,000
Therefore the place value is 7,00,000
c)
Greatest 7 digit number is 99,99,999
Adding 1 to it = 99,99,999 + 1 = 1,00,00,000
d)
85642 = 80000 + 5000 + 600 + 40 +2
e)
round off 85642 to nearest thousand = 86,000
Number 16- 216
number 17- 180
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