Question

A biology test is worth 100 points and has 36 questions.

Answer 1

Answer:

(a) 7 essays and 29 multiple questions

(b) Your friend is incorrect

Step-by-step explanation:

Represent multiple choice with M and essay with E.

So:

$M + E= 36$ --- Number of questions

$2M + 6E = 100$ --- Points

Solving (a): Number of question of each type.

Make E the subject of formula in $M + E= 36$

$E = 36 - M$

Substitute 36 - M for E in $2M + 6E = 100$

$2M + 6(36 - M) = 100$

$2M + 216 - 6M = 100$

Collect Like Terms

$2M - 6M = 100 - 216$

$-4M = - 116$

Divide both sides by -4

$M = \frac{-116}{-4}$

$M = 29$

Substitute 29 for M in $E = 36 - M$

$E = 36 - 29$

$E = 7$

Solving (b): Can the multiple questions worth 4 points each?

It is not possible.

See explanation.

If multiple question worth 4 points each, then

$2M + 6E = 100$ would be:

$4M + xE = 100$

Where x represents the number of points for essay questions.

Substitute 7 for E and 29 for M.

$4 * 29 + x * 7 = 100$

$116 + 7x = 100$

Subtract 116 from both sides

$116-116 + 7x = 100 -116$

$7x = 100-116$

$7x = -16$

Make x the subject

$x = -\frac{16}{7}$

Since the essay question can not have worth negative points.

Then, it is impossible to have the multiple questions worth 4 points

Your friend is incorrect.