Brady 86555 5 3/4" Height x 3" Width, Economy Polyester (B-851), Red on White Ladder Tags (10 Tags)

this is calculator question number 18 for practice test six in the 2018 college board prep book which is also October 2016 SAT close board gives you a diagram paragraph about designing stairs with the riser cred formula two h plus D equals 25 and they asked what's the possible range of values for H if billing codes require tread depth D at least nine and riser height H at least five so if d is at least nine then 2h plus nine equals 25 when D is exactly nine so two H equals sixteen if I subtract 9 from both sides to get the 2 H by itself divided by 2 and H equals 16 over 2 equals 8 so at D equals 9 H would be 8 and if d is greater than 9 will subtract more than 9 for 25 and H will be less than 8 so an upper bound of 8 as in choice C matches that and we're told riser height H must be at least 5 which also matches choice C the correct answer would be C call it board off and asked you to ev