diff --git a/front_end/src/utils/math.ts b/front_end/src/utils/math.ts
index c0065166a0..c87e6dc070 100644
--- a/front_end/src/utils/math.ts
+++ b/front_end/src/utils/math.ts
@@ -267,14 +267,20 @@ export function unscaleNominalLocation(x: number, scaling: Scaling) {
  */
 export function getCdfAt(x: number, cdf: number[], scaling: Scaling) {
   const location = unscaleNominalLocation(x, scaling);
-  const floatIndex = location * (cdf.length - 1);
-  if (floatIndex <= 0) {
+  if (location <= 0) {
     return cdf.at(0);
   }
-  if (floatIndex >= 1) {
+  if (location >= 1) {
     return cdf.at(-1);
   }
-  return cdf.at(Math.round(floatIndex));
+  const floatIndex = location * (cdf.length - 1);
+  // linear interpolation
+  const lowerIndex = Math.floor(floatIndex);
+  const upperIndex = Math.ceil(floatIndex);
+  const weight = floatIndex - lowerIndex;
+  /* eslint-disable @typescript-eslint/no-non-null-assertion */
+  return cdf[lowerIndex]! * (1 - weight) + cdf[upperIndex]! * weight;
+  /* eslint-enable @typescript-eslint/no-non-null-assertion */
 }
 
 /**
diff --git a/front_end/src/utils/questions/helpers.ts b/front_end/src/utils/questions/helpers.ts
index f20b0f937e..f5f8dbe96b 100644
--- a/front_end/src/utils/questions/helpers.ts
+++ b/front_end/src/utils/questions/helpers.ts
@@ -135,15 +135,11 @@ export function getContinuousGroupScaling(
     range_min: rangeMinPoints.length > 0 ? Math.min(...rangeMinPoints) : null,
     // set zero_point to null if any are linearly scaled
     zero_point:
-      zeroPoints.length > 0 && !zeroPoints.some((p) => p !== null)
-        ? Math.min(...zeroPoints)
-        : null,
+      zeroPoints.length === questions.length ? Math.min(...zeroPoints) : null,
   };
-  // we can have mixes of log and linear scaled options
-  // which leads to a derived zero point inside the range which is invalid
-  // so just ignore the log scaling in this case
+  // if zero_point ends up lying within the range, remove the scaling
   if (
-    scaling.zero_point !== null &&
+    !isNil(scaling.zero_point) &&
     !isNil(scaling.range_min) &&
     !isNil(scaling.range_max) &&
     scaling.range_min <= scaling.zero_point &&