The ph scale measures how acidic or basic a substance is. lemon juice is said to have a ph of less than 4 and greater than 1.5. model the normal range of ph values of lemon juice, using a compound inequality.
1.5 > x > 4
1.5 < x < 4
1.5 ≤ x ≤ 4
1.5 ≥ x ≥ 4

Inequalities are used  to relate unequal expressions.

The compound inequality that represents the normal range of pH values of lemon juice: (b) 1.5 < x < 4

Let the pH of lemon juice be represented with x.

x less than 4 means: x < 4

x greater than 1.5 means x > 1.5

So, we have:

x < 4 and x > 1.5

Rewrite as:

x > 1.5 and x < 4

Express x > 1.5 as 1.5 < x

1.5 < x and x < 4

Combine the inequalities

1.5 < x < 4

Hence, the required compound inequality is: (b) 1.5 < x < 4

Read more about inequalities at:

link

Let's say x is J because it's Lemon Juice.

It's said that the pH of J is less than 4 so: pH(J) < 4 and pH(J) is greater than 1.5 so: pH(J) > 1.5

Now we can construct:

Or simply:

We can also write this with an interval:

Hope this helps.

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