Among smartphone users, 40% use a case but no screen protector, 10% use a screen protector but no case, 45% use both a case and a screen protector, and 5% use neither a case nor a screen protector. Twenty smartphone users are sampled at random. Let X1, X2, X3, X4 be the respective numbers of users in the four given categories.

Find P(X1=7, X2=3, X3=8, X4=2).

first, we define the variables:

x: number of years after 1950

f (x): amount of vinyl sold.

then, with the variables defined, we have:

68594 vinyl records were sold in 1958 > f (8) = 68594

91299 vinyl records were sold in 1961 > f (11) = 91299

38720 vinyl records were sold in 1952 > f (2) = 38720

161743 vinyl records were sold in 1967 > f (17) = 161743

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step-by-step explanation:

2,160 π

step-by-step explanation:

1st part is 64,000,000

2nd part 500,000

step-by-step explanation:

answer:

some responsibilities that come with having a checking account -

1. we have to maintain check register with exactness to avoid checks being returned for insufficient funds which is called bouncing a check.

2. we need to update our check register each time we make a transaction using a convenience card. updating check register will   save   us from   overdrawing of checking account.

3. read the agreement the bank gave you when you signed up for our checking account. this includes all the fees and the minimum balance we need to keep in our account to avoid maintenance charges.  

explanation:

note : -   checking account is a transactional deposit account. we can use it to deposit and withdraw funds. money in a checking account is very liquid. it   can be withdrawn using electronic debits, automated cash machines, or checks among other methods.