I run 12 miles in 90 minutes. What is my average speed in miles per hour?

First convert 90 minutes to hours: 90 minutes / 60 minutes/hours =

<<90/60=1.5>>1.5 hours. In 1 hour, I run 12 miles / 1.5 hours = <<12/1.5=8>>8 miles/hour. #### 8 Chenny bought 9 plates at $2 each. She also bought spoons at $1.50 each. How many spoons did Chenny buy if she paid a total of $24 for the plates and spoon? The cost of 9 plates is $2 x 9 = $<<2*9=18>>18. So, Chenny paid $24 - $18 = $<<24-18=6>>6 for the spoons. Therefore, she bought $6/$1.50 = <<6/1.5=4>>4 spoons. #### 4 Spike the bearded dragon eats crickets to get protein in his diet. He hunts 5 crickets every morning and three times that over the afternoon and evening, munching on leafy greens and other vegetation in between. How many crickets does Spike hunt per day? Spike hunts 3 * 5 = <<3*5=15>>15 crickets in the afternoon and evening. Hence, he hunts 5 + 15 = <<5+15=20>>20 crickets per day. #### 20 It takes Derek 9 minutes to walk a mile if he doesn't have to walk with his brother. If he has to take his brother it takes 12 minutes to walk a mile. How many minutes longer would it take him to walk 20 miles if he had to take his brother? Alone it would take him 9*20=<<9*20=180>>180 minutes With his brother, it would take him 12*20=<<12*20=240>>240 minutes 240-180=<<240-180=60>>60 more minutes #### 60 Joe and Adam built a garden wall with three courses of bricks. They realized the wall was too low and added 2 more courses. If each course of the wall had 400 bricks, and they took out half of the bricks in the last course to allow easy checkup of the garden, calculate the total number of bricks the wall has. When they added two more courses for the wall, the number of courses became 3+2 = <<3+2=5>>5 Since each course has 400 bricks, the total number of bricks for 5 courses is 5*400 = <<5*400=2000>>2000 To allow for an easy checkup of the wall, they removed 1/2*400 = <<1/2*400=200>>200 bricks from the last course of the wall. In total, the wall has 2000-200= <<2000-200=1800>>1800 bricks. #### 1800 During a unit on probability, a teacher surveys her class asking her students two questions. The first question was whether they prefer dogs or cats, and the second question was whether they movies or video games. Of the 30 students in her class, 50% chose dogs and video games as their two answers, while 10% chose dogs and movies as their two answers. In total, how many students in this teacher's class prefer dogs over cats? The 50% of the class that chose dogs and video games amounts to 30*0.5 = <<50*.01*30=15>>15 students who prefer dogs over cats. Similarly, the 10% that chose dogs and movies amount to 30*0.1 = <<30*0.1=3>>3 students who prefer dogs over cats. Because these are the only two ways that a student could indicate their preference for dogs, and because these groups do not overlap, a total of 15 + 3 = <<15+3=18>>18 students favor dogs over cats in this teacher's class. #### 18 Rosie pays for a $.44 piece of candy with a $1 bill. If the cashier gives her the smallest number of coins possible as change, how many coins will Rosie get as change? Rosie will get $1-$.44=$<<1-.44=.56>>.56 in change. She will get 2 quarters to account for $.50 of the change. She will also get 1 nickel to account for $.05 of the change. Then, she will get 1 penny, to account for the last $.01 of the change. She will get 2+1+1 = <<2+1+1=4>>4 coins total. #### 4 Ella spends 40% of the money she makes from babysitting on video games. Last year she spent $100. This year she received a 10% raise. What is Ella’s new salary? Last year Ella made a total of $100 / (40/100) = $<<100/(40/100)=250>>250 This year with her raise, Ella’s salary will be $250 * (110/100) = $<<250*(110/100)=275>>275 #### 275 Mr. Maxwell takes 1 hr to drive to work in the morning but 1 and half hours to drive back home in the evening. If the morning and evening traffic is similar and he drives at an average speed of 30mph in the morning, what is the average speed of his return journey? In the morning he travels at an average speed of 30mph for 1 hour so he covers a distance of 30*1 = <<30*1=30>>30 miles He covers the same distance of 30 miles in the evening spending 1.5 hours so his average speed must be 30/1.5 = <<30/1.5=20>>20mph #### 20 Scott runs 3 miles every Monday through Wednesday. Then he runs twice as far he ran on Monday every Thursday and Friday. How many miles will he run in a month with 4 weeks? Scott runs 3 x 2 = <<3*2=6>>6 miles every Thursday and Friday. The total miles run by Scott for a week from Monday through Wednesday is 3 x 3 = <<3*3=9>>9 miles. The total miles run by Scott for a week from Thursday to Friday is 6 x 2 = <<6*2=12>>12 miles. So, in a week, Scott runs a total of 9 + 12 = <<9+12=21>>21 miles. Thus, he runs a total of 21 x 4 = <<21*4=84>>84 miles in a month. #### 84