[計量] 五題計量問題?
Q1. The arithmetic mean and standard deviation of a certain
normal distribution are 13.5 and 1.5, respectivly.What value
is exactly 2 standard deviations less than the mean?
Ans:10.5
Q2. One week a certain truck rentak lot had a total of 20
trucks, all of which were on the lot Monday morning.
If 50 percent of the trucks that were rented out during
the week were returned to the lot on or before Saturday
morning of that week, and if there were at least 12 trucks
on the lot that Saturday morning, what is the greatest
number of different trucks that could have been rented out
during the week?
Ans:16
Q3. Two trains, X and Y started simultaneously from opposite
ends of a 100-mile route and traveled toward each other on
parallel tracks. Train X travling at constant rate, completed
the 100-mile trip in 5 hours; train Y traveling at a constant
rate, completed the 100-mile trip in 3 hours. How many mile
had train X traveled when it met train Y?
Ans: 37.5
Q4. A tourist purchased a total of $1500 worth of travler's checks
in $10 and $50 denominations. During the trip the tourist cached
7 checks and then losts all of the rest. If the number of $10 checks
cashed was one more or one less than the number of $50
checks cashed, what is the minimum possible value of the checks
that were lost?
Ans: $1,270
Q5. Coins are to be put into 7 pockets so that each pocket contains at least
one coin. At most 3 of the pockets are to contain the same number of coins
and no two of the remaining pockets are to contain an equal number
of coins. What is the least possible number of coins needed for the
pockets?
Ans: 17
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