Okay, so there are two problems that I can't solve & that's why I'm posting it here [BTW, I didn't find any forum for Arithmetic, so I chose to post it here]

These problems were found in a GRE book in Easy-Modrate difficulty section

The problems are: -

Problem No 1.

Diane has 18 errands to run, which take 14 minutes each, before she can go home. If Diane needs to be home by 5:00 pm, what's the latest time that she can start the errands?

a. 11:40 am

b. 11:48 am

c. 12:40 pm

d. 12:48 pm

e. 1:40 pm

Now as for this problem, I first calculated the total time Diane would need to run all the errands by 18x14 mins, which gave me the result 252 mins. Then I divided 252/60, which gave me the result 4.2 hours. But after I tried to subtract 4.2 hrs from 5 pm or 17 hrs [12 hrs + 5 hrs], it gave me the result 12.8 hrs [12 hrs & 80 mins] or 1: 20 pm.

But this isn't listed on the choices. So where did I go wrong??

We have 4.2 hours = 4 hours and 12 minutes (since 0.2 of 60 minutes is 12), and thus 5 - 4.2 = 1.8 = 1 hour and 48 minutes.
Problem No 2.

Sheila can wear her 100% linen suit four times before she needs to have it dry cleaned. She wears the suit to Church every Sunday and to meeting at bridge club on the first Tuesday of every month. If it costs $8.00 for each individual cleaning, and Sheila does not wear the suit on any other occasions, how much will Sheila pay to dry clean the suit each year?

a. $48.00

b. $64.00

c. $96.00

d. $104.00

c. $128.00

Now what I did here is that I first calculated how many Sundays & Tuesday there were in a year. On average, there are 4 Sunday a month, so that would make it upto 48 Sundays in a year. So then I added 48 to 12, and got 60. This is how many times Sheila would wear the suit in a year. Then I divided 60/4, got 15 & multiplied 15 x $8, which gave me $120 as the result. But sadly, even this one wasn't listed on the choices.

So where the heck am I getting it wrong every time???