Difficult Math Prob - SM Extra Practice 5 Answers/Help

[KBadd]

Is there a place online where Singapore Math has a list of errors in their Teacher Manuals/Answer Keys?  I know I've spotted a couple of errors over the years.

We're using Extra Practice 5 this year and I cannot figure out how they arrived at the answer given in the Answer Key in the back of the book.  I double checked our work, but we keep getting a different answer than the one given.  Can anyone tell me if they know the answer, or what answer you get when you try to solve it?  Curious if we are wrong or the book is wrong ;)

It's Exercise 46 #9:  In the rectangular tank shown below, the volume of the water only is 19.2 liters.  When the iron ball is removed from the tank, the water level drops by 5 cm.  Find the volume of the iron ball.  (1 liter = 1,000 cm3).  (The rectangle shown has a length of 40 cm and the water's height level (with the ball in the tank) is 20 cm.)

 

[sweet2ndchance]

I used the same method and got the same answer Square did; 6400 cubic centimeters is the volume of the iron ball.

 

[Noreen Claire]

Errata found here: https://www.singaporemath.com/errata/

"Change  first  sentence  to:                                                                                                            In the  rectangular  tank  shown below,  the  volume  of  the  water  and the  iron ball  is 19.2  L."

[sweet2ndchance]

Here's what I came up with by I'm half asleep so someone check me...

Find the missing width measurement

40 * W * 20 = 19,200 cm^3

800 * W = 19,200

W = 24

Find the volume of the tank without the ball

40 * 24 * 15 = 14, 400 cm^3

Find the volume of the ball

19,200 - 14,400 = 4,800 cm^3