Of 30 snakes at the reptile house, 10 have stripes, 21 are poisonous,

Question

Of 30 snakes at the reptile house, 10 have stripes, 21 are poisonous, and 5 have no stripes and are not poisonous. How many of the snakes have stripes AND are poisonous?

A. 4
B. 6
C. 9
D. 15
E. 20

Kudos for a correct  solution .

balamoon · Answer

Of 30 snakes at the reptile house, 10 have stripes, 21 are poisonous, and 5 have no stripes and are not poisonous. How many of the snakes have stripes AND are poisonous?

A. 4
B. 6
C. 9
D. 15
E. 20

Solution -

Total = Stripes + Poisonous - Both + Neither
30 = 10 + 21 + 5 - Both - > Both = 6

the snakes have both stripes AND are poisonous = 6

Carcass · Answer

You do not need a grid

A + B - Both + Neither

10+21-B+5=30

B=6

regards

GMATinsight · Answer

In My opinion, Such questions can be best slved by Bouble Matrix Method

Answer: Option B

LaxAvenger · Answer

Total = a +b - both + neither

30= 10 + 21 - x + 5

x = 6. Answer B

TimeTraveller · Answer

Total = 30 = T

Let snakes with stripes be X, and snakes that are poisonous be Y. Snakes that have neither stripes nor are poisonous be Z.

X (AND) Y = (X + Y) - (T - Z) = (10+21) - (30-5) = 31-25 = 6.

mejia401 · Answer

30 = 10 + 21 + 5 - Double 
 Double = 6

For the seemingly easy questions, I also try to work through logically the answers (even though I already have the answer):

A. 4  if neither include 5 and non-poisonous total is 9, then both cannot be less than 6 
B. 6  True. 
C. 9  if neither include 5 and non-poisonous total is 9, then both cannot be higher than 6 
D. 15  Not true. It cannot be greater than number of the snakes that have stripes 
E. 20  Not true. It cannot be greater than number of the snakes that have stripes

B.

chetan2u · Answer

....p.....np
s.. 6 .....4.....10
ns.15..5.....20
t...21..9......30
ans 6 B

ENGRTOMBA2018 · Answer

Set up a 2X2 grid to solve this question:

\begin{tabular}{| l | l | l | l |}
 \hline
 & Stripe & Not Stripe & Total \ \hline
 Poisonous & 6 & 15 & 21 \ \hline
 Not Poisonous & 4 & 5 & 9\ \hline
 Total & 10 & 20 & 30 \
 \hline
 \end{tabular}

Bunuel · Answer

MANHATTAN GMAT OFFICIAL SOLUTION: https://gmatclub.com/forum/download/file.php?id=27163 Use a Double-Set Matrix to solve this problem. First, fill in the numbers given in the problem: 30 snakes, 10 with stripes (and therefore 20 without), 21 that are poisonous (and therefore 9 that are not), and 5 that are neither striped nor poisonous. Use subtraction to fill in the rest of the chart. Thus, 6 snakes have stripes and are poisonous. Answer: B. 2015-07-06_1452.png

ScottTargetTestPrep · Answer

We can create the equation:

Total = #Stripes + #Poisonous - Both + Neither

30 = 10 + 21 - Both + 5

30 = 36 - Both

Both = 6

Answer: B

vanquynh285 · Answer

We have equation: Total = Only stripe + Only poisonous + Neither stripe or poisonous - Stripe and poisonous
30 = 10 + 21 + 5 - Stripe and poisonous
--> Stripe and poisonous = 6

Of 30 snakes at the reptile house, 10 have stripes, 21 are poisonous,

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GMAT Problem Solving (PS) Questions

Of 30 snakes at the reptile house, 10 have stripes, 21 are poisonous,

Prep Toolkit

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My Rewards