CAT 1995 | Question: 55

Question

What is the value of m which satisfies $3m^{2} - 21m + 30 < 0$?

• A. $m < 2$, or $m > 5$ 
• B. $m > 2$ 
• C. $2 < m < 5$ 
• D. $m < 5$

Answer 1

$3m^{2}-21m+30< 0$

$A.m<2 , or \ \ m>5$

Option A fails when m=0

$3(0)^{2}-21 \times 0+30=30$

Hence,Option A is false.

$B.m>2$

Option B fails when m=5 

$3 \times 5^{2}-21 \times 5+30=0$

Hence,Option B is false.

$C.2<m<5$

when m=3

$3\times3^{2}-21 \times 3 +30=-6$

when m=4

$3\times4^{2}-21 \times 4 +30=-6$

Hence,Option(C) is true.

$D.m<5$

Option D fails when m=2

$3 \times 2^{2}-21 \times 2+30= 0$

 

Hence,Option(C)$2<m<5$ is the correct choice.